Dormant mode measurement optimization

ABSTRACT

Methods performed by a wireless device operating in a dormant mode comprise performing a measurement on each of a plurality of resources from a predetermined set of resources or demodulating and decoding information from each of a plurality of resources from a predetermined set of resources, such as a set of beams. The methods further include evaluating the measurement or the demodulated and decoded information for each of the plurality of resources against a predetermined criterion, and then discontinuing the performing and evaluating of measurements, or discontinuing the demodulating and decoding and evaluation of information, in response to determining that the predetermined criterion is met, such that one or more resources in the predetermined set of resources are neither measured nor demodulated and decoded. The methods further comprise deactivating receiver circuitry, further in response to determining that the predetermined criterion is met.

TECHNICAL FIELD

The present disclosure is generally related to the performing ofmeasurements for radio resource management, and is more particularlyrelated to methods and apparatus for performing measurements in dormantmode.

BACKGROUND

In any cellular system, it is of very high importance that batterypowered, mobile nodes (hereafter referred to as “user equipments,” or“UEs”) can spend most of their time in a low activity state to preserveenergy. Typically, a cellular system will have one or more defined“active” modes, where the UE is controlled by the network and isinstructed to attach to a certain cell, do certain measurements etc. Thesystem will generally also have one or more “idle” or “dormant” modes,where the UE typically listens only to certain signals from the networkand makes its own decisions regarding which cell or cells to listen to,and when to report back status updates.

Most UEs in most cellular systems today spend a majority of their timein dormant mode, and therefore it is of utmost importance that the UEscan consume as little power as possible in dormant mode.

In a cellular system like as the 5^(th)-generation radio access network(RAN) currently being defined by the 3^(rd)-Generation Partnership(3GPP) and often referred to as “New Radio” or “NR,” beamforming can beused for the transmission of cell information signals. “Beamforming”here refers to a (usually) highly directional transmission of the signalenergy for a given signal or set of signals, e.g., with 3-dB beam-widthsof less, often substantially less, than 90 degrees in the horizontalplane, for downlink transmissions. While conventional transmissions areshaped to some degree, e.g., to avoid transmitting excessive energy in avertical direction and/or to direct the majority of the signal energy toa particular cell sector, the beamformed transmissions discussed hereinare intentionally shaped to a greater extent, so that, for example, anygiven downlink beam provides useful signal strengths only within a smallfraction of the area that is generally served by the transmitting node.Accordingly, to serve the entire area, the transmitting node may makeuse of multiple, and perhaps very many, beams, which may betime-multiplexed, frequency-multiplexed, or both.

Beamforming cell information signals or broadcast signals, such asso-called mobility reference symbols, rather than transmitting them overan entire cell, may be done for several reasons. One reason is toincrease the effective antenna gain of the transmitter, e.g., tocompensate for higher path loss in high frequency bands or to enableextended coverage at traditional frequencies. Another reason is toobtain a rough spatial positioning of a UE, based on the directionalityof the beam.

Typically, the beamformed cell information signals will be timemultiplexed between beams so that high output power can be used for eachbeam.

SUMMARY

With beamformed cell information signals, there is a multiplicationfactor introduced with respect to the number of signals that a UE indormant mode must search for and measure. In a conventional system wherecell information is not beam-formed, there is typically one signal tomeasure for each “cell”—for the same kind of “cell” where cellinformation is beamformed, there can be several tens of signals orbeams, such as beams carrying mobility reference signals, to search for.This can increase the power consumption for a UE in dormant mode,especially if the signals are time multiplexed, as search for such beamsrequires the UE receiver to be on over long durations of time.

Embodiments disclosed herein to address these problems include methodsperformed by a UE or other wireless device that is operating in adormant mode, where operating in the dormant mode comprisesintermittently activating receiver circuitry to monitor and/or measuresignals. These methods comprise, while the wireless device is in thisdormant mode, and while the receiver circuitry is activated, performinga measurement on each of a plurality of resources from a predeterminedset of resources or demodulating and decoding information from each of aplurality of resources from a predetermined set of resources, where theresources in the predetermined set of resources are each defined by oneor more of a beam, a timing, and a frequency. In some embodiments, theresources in this predetermined set of resources are each defined as abeam. The methods further include evaluating the measurement or thedemodulated and decoded information for each of the plurality ofresources against a predetermined criterion, and then discontinuing theperforming and evaluating of measurements, or discontinuing thedemodulating and decoding and evaluation of information, in response todetermining that the predetermined criterion is met, such that one ormore resources in the predetermined set of resources are neithermeasured nor demodulated and decoded. The methods further comprisedeactivating the activated receiver circuitry, further in response todetermining that the predetermined criterion is met.

In some embodiments, the predetermined criterion comprises one or moreof the following: that a received power level, or a measuredsignal-to-interference-plus-noise ratio (SINR), or a signal-to-noiseratio (SNR) is above a predetermined threshold, for one or for apredetermined number of resources; that cell information can becorrectly decoded from one or for a predetermined number of resources;and that decoded information from one or for a predetermined number ofresources instructs a change in operation for the wireless device.

In some embodiments, the discontinuing is performed in response todetermining that the predetermined criterion is met for one of theresources. In some embodiments, the method further comprises, prior tosaid performing or demodulating and decoding, and prior to saidevaluating, discontinuing, and deactivating, determining a priorityorder for the predetermined set of resources, from highest to lowest,wherein said performing or demodulating and decoding is according to thepriority order, from highest to lowest. This determining the priorityorder for the predetermined set of resources may be based on one or moreof any of the following, for example: radio resource timing for one ormore of the resources; and measured signal qualities or measurementproperties from previous measurements of one or more of the resources.In some embodiments, determining the priority order for thepredetermined set of resources is based on information regardinglikelihood of usefulness for one or more of the resources, theinformation being received from other sources or cell neighbour lists.

Other embodiments disclosed herein include wireless devices adapted tocarry out a method according to any of those summarized above, as wellas corresponding computer program products and computer-readable media.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a high-level logical architecture for NR and LTE.

FIG. 2 shows an NR and LTE logical architecture.

FIG. 3 illustrates LTE/NR UE states.

FIG. 4 includes a block diagram of filtered/windowed OrthogonalFrequency-Division Multiplexing (OFDM) processing and shows mapping ofsubcarriers to time-frequency plane.

FIG. 5 shows windowing of an OFDM symbol.

FIG. 6 illustrates basic subframe types.

FIG. 7 illustrates an example construction of a mobility and accessreference signal (MRS).

FIG. 8 shows tracking area configuration.

FIG. 9 is a signal flow diagram illustrating a Tracking RAN Area (TRA)update procedure.

FIG. 10 shows options for beam shapes.

FIG. 11 is a signaling flow diagram illustrating an active-mode mobilityprocedure.

FIG. 12 is a signaling flow diagram illustrating beam selection based onuplink measurement.

FIG. 13 is a signaling flow diagram illustrating intra-node beamselection based on uplink measurement.

FIG. 14 is a process flow diagram illustrating an example method in awireless device.

FIG. 15 is a process flow diagram illustrating another example method ina wireless device.

FIG. 16 is a process flow diagram illustrating still another examplemethod in a wireless device.

FIG. 17 is a block diagram illustrating an example wireless device.

FIG. 18 is a block diagram illustrating example radio network equipment.

FIG. 19 is another block diagram illustrating an example wirelessdevice.

DETAILED DESCRIPTION

As discussed above, beamforming of cell information signals createspotential problems with respect to power consumption for wirelessdevices, or UEs, operating in dormant mode. In a conventional systemwhere cell information is not beam-formed, there is typically one signalto measure for each cell, where “cell” refers to the geographical areacovered by the signals transmitted by a cellular network accesspoint—for the same kind of cell where cell information is beamformed,there can be several tens of signals or beams, such as beams carryingmobility reference signals, to search for. This can increase the powerconsumption for a UE in dormant mode, especially if the signals are timemultiplexed, as search for such beams requires the UE receiver to be onover long durations of time.

The techniques and apparatus described herein address these problems byreducing or limiting the power consumption in dormant mode in a cellularsystem using beamformed cell information signals, e.g., in a system like3GPP's NR system. The techniques and apparatus described herein do thisby restricting the measurement and cell search sequence in the UE, basedon the signal quality of the beamformed cell information signals thathave already been measured. For each measurement instance, the UE canfocus its search on previously known strong signals and simultaneouslysearch for new cells on that carrier. If the previously known strongsignals are verified to be strong enough, the measurement sequence canbe stopped, so that the UE need not search for every possible cellinformation signal. Likewise, if one or a predetermined number of cellinformation signals are received and determined to be strong enough, themeasurement sequence can be stopped, again so that the UE does notsearch for every cell information signal in a predetermined set ofsignals among which the search is performed.

An advantage of several of the embodiments described herein is that themeasurement durations for a UE in dormant mode can be drasticallyreduced in those circumstances where the UE can quickly determine thatit has “good enough” signal quality for one or more cell informationsignals, where “good enough” means that the signal quality meets one ormore predetermined criteria.

Details of these techniques and apparatus, including a detaileddescription of several specific embodiments, are provided below. First,however, descriptions of several concepts, system/network architectures,and detailed designs for several aspects of a wireless communicationsnetwork targeted to address the requirements and use cases forfifth-generation networks (referred to as “5G”) are presented, toprovide context for the disclosure of the dormant mode operations thatfollow. It should be appreciated, however, that an actual 5G network mayinclude none, some, or all of the detailed features described below. Itwill further be appreciated that the techniques and apparatus describedherein for performing measurements in dormant mode are not limited toso-called 5G networks, but may be used in and/or adapted for otherwireless networks.

In the discussion that follows, the wireless communications network,which includes wireless devices, radio access networks, and corenetworks, is referred to as “NR.” It should be understood that the term“NR” is used herein as simply a label, for convenience. Implementationsof wireless devices, radio network equipment, network nodes, andnetworks that include some or all of the features detailed herein may,of course, be referred to by any of various names. In future developmentof specifications for 5G, for example, other terms may be used—it willbe understood that some or all of the features described here may bedirectly applicable to these specifications. Likewise, while the varioustechnologies and features described herein are targeted to a “5G”wireless communications network, specific implementations of wirelessdevices, radio network equipment, network nodes, and networks thatinclude some or all of the features detailed herein may or may not bereferred to by the term “5G.”

NR targets new use cases, e.g. for factory automation, as well asExtreme Mobile Broadband (MBB), and may be deployed in a wide range ofspectrum bands, calling for high degree of flexibility. Licensedspectrum remains a cornerstone for NR wireless access but unlicensedspectrum (stand-alone as well as license-assisted) and various forms ofshared spectrum (e.g. the 3.5 GHz band in the US) are nativelysupported. A wide range of frequency bands are supported, from below 1GHz to almost 100 GHz. It is of principal interest to ensure that NR canbe deployed in a variety of frequency bands, some targeting coverage atlower frequency regions below 6 GHz, some providing a balance ofcoverage, outdoor-to-indoor penetration and wide bandwidth up to 30 GHz,and finally some bands above 30 GHz that will handle wide bandwidth usecases, but possibly at a disadvantage to coverage and deploymentcomplexity. Both FDD and dynamic TDD, where the scheduler assigns thetransmission direction dynamically, are part of NR. However, it isunderstood that most practical deployments of NR will likely be inunpaired spectrum, which calls for the importance of TDD.

Ultra-lean design, where transmissions are self-contained with referencesignals transmitted along with the data, minimizes broadcasting ofsignals. Terminals make no assumptions on the content of a subframeunless they are scheduled to do so. The consequence is significantlyimproved energy efficiency as signaling not directly related to userdata is minimized

Stand-alone deployments as well as tight interworking with LTE aresupported. Such interworking is desirable for consistent user experiencewith NR when used at higher frequency ranges or at initial NR rolloutwith limited coverage. The radio-access network (RAN) architecture canhandle a mix of NR-only, LTE-only, or dual-standard base stations. TheeNBs (“evolved Node Bs,” 3GPP terminology for a base station) areconnected to each other via new interfaces that are expected to bestandardized. It is envisioned that these new interfaces will be anevolution of the existing S1 and X2 interfaces to support features suchas network slicing, on demand activation of signals, user plane/controlplane splits in the core network (CN), and support for a new connecteddormant state, as described herein. As described below, LTE-NR basestations may share at least integrated higher radio interface protocollayers, such as the Packet Data Convergence Protocol (PDCP) and RadioResource Control (RRC) layers, as well as a common connection to theevolved packet core (EPC).

NR separates dedicated data transmissions from system access functions.The latter include system information distribution, connectionestablishment functionality, and paging. Broadcast of system informationis minimized and not necessarily transmitted from all nodes handlinguser-plane data. This separation benefits beamforming, energyefficiency, and support of new deployment solutions. In particular, thisdesign principle allows densification to increase the user-planecapacity without increasing the signaling load.

A symmetric design with OFDM in both the downlink and the uplinkdirections is detailed below. To handle the wide range of carrierfrequencies and deployments, a scalable numerology may be used. Forexample, a local-area, high-frequency node uses a larger subcarrierspacing and a shorter cyclic prefix than a wide-area, low-frequencynode. To support very low latency, a short subframe with fast ACK/NACK(acknowledgement/negative acknowledgement) is proposed, with thepossibility for subframe aggregation for less latency-critical services.Also, contention-based access is part of NR, to facilitate fast UEinitiated access. New coding schemes such as polar codes or variousforms of Low-Density Parity Check (LDPC) codes may be used, instead ofturbo codes, to facilitate rapid decoding of high data rates with areasonable chip area. Long discontinuous-receive (DRX) cycles and a newUE state, RRC dormant, where the UE RAN context is maintained, allowfast transition to active mode with reduced control signaling.

Enabling full potential of multi-antenna technology is a cornerstone ofthe NR design. Hybrid beamforming is supported and advantages withdigital beam forming are exploited. User-specific beamforming throughself-contained transmission is advantageous for coverage, especially athigh frequencies. For the same reason, UE transmit (TX) beamforming isproposed as an advantageous component, at least for high frequencybands. The number of antenna elements may vary, from a relatively smallnumber of antenna elements (e.g., 2 to 8) in LTE-like deployments tomany hundreds, where a large number of active or individually steerableantenna elements are used for beamforming, single-user MIMO and/ormulti-user MIMO to unleash the full potential of massive MIMO. Referencesignals and Medium Access Control (MAC) features are designed to allowexploiting reciprocity-based schemes. Multi-point connectivity, where aterminal is simultaneously connected to two or more transmission points,can be used to provide diversity/robustness, by transmitting the samedata from multiple points.

NR includes a beam-based mobility concept to efficiently supporthigh-gain beam forming. This concept is transparent to both inter- andintra-eNB beam handover. When the link beams are relatively narrow, themobility beams should be tracking UEs with high accuracy to maintaingood user experience and avoid link failure. The mobility conceptfollows the ultra-lean design principle by defining a set ofnetwork-configurable downlink mobility reference signals that aretransmitted on demand, when mobility measurements from the UE areneeded. Uplink measurement based mobility may also be used, withsuitable base stations supporting reciprocity.

5G Mobile Broadband (MBB) services will require a range of differentbandwidths. At the low end of the scale, support for massive machineconnectivity with relatively low bandwidths will be driven by totalenergy consumption at the user equipment. In contrast, very widebandwidths may be needed for high capacity scenarios, e.g., 4K video andfuture media. The NR air interface focuses on high bandwidth services,and is designed around availability of large and preferably contiguousspectrum allocations.

High-level requirements addressed by the NR system described hereininclude one or more of:

-   -   1) Support for higher frequency bands with wider carrier        bandwidth and higher peak rates. Note that this requirement        motivates a new numerology, as detailed below.    -   2) Support for lower latency, which requires shorter and more        flexible Transmission Time Intervals (TTIs), new channel        structures, etc.    -   3) Support for very dense deployments, energy efficient        deployments and heavy use of beam forming, enabled by, for        example removing legacy limitations in relation to Cell-specific        Reference Signal (CRS), Physical Downlink Control Channel        (PDCCH), etc.    -   4) Support of new use cases, services and customers such as        Machine-Type Communication (MTC) scenarios including so-called        vehicle-to-anything (V2X) scenarios, etc. This can include more        flexible spectrum usage, support for very low latency, higher        peak rates etc.

Following is a description of the NR architecture, followed by adescription of the radio interface for NR. Following that is adescription of a variety of technologies and features that are supportedby the NR architecture and radio interface. It should be understood thatwhile the following detailed description provides a comprehensivediscussion of many aspects of a wireless communications system, wherenumerous advantages are obtained by combinations of many of thedescribed features and technologies, it is not necessary for all thetechnologies and features described herein to be included in a systemfor the system to benefit from the disclosed technologies and features.For example, while details of how NR may be tightly integrated with LTEare provided, a standalone version of NR is also practical. Moregenerally, except where a given feature is specifically described hereinas depending on another feature, any combination of the manytechnologies and features described herein may be beneficial.

The NR architecture supports both stand-alone deployments anddeployments that may be integrated with LTE or, potentially, any othercommunication technology. In the following discussion, there is a lot offocus on the LTE integrated case. However, it should be noted thatsimilar architecture assumptions also apply to the NR stand-alone caseor to integration with other technologies.

FIG. 1 shows the high level logical architecture for an example systemsupporting both NR and LTE. The logical architecture includes bothNR-only and LTE-only eNBs, as well as eNBs supporting both NR and LTE.In the illustrated system, the eNBs are connected to each other with adedicated eNB-to-eNB interface referred to here as the X2* interface,and to the core network with a dedicated eNB-to-CN interface referred tohere as the S1* interface. Of course, the names of these interfaces mayvary. As seen in the figure, a core network/radio access network(CN/RAN) split is evident, as was the case with the Evolved PacketSubsystem (EPS).

The S1* and X2* interfaces may be an evolution of the existing S1 and X2interfaces, to facilitate the integration of NR with LTE. Theseinterfaces may be enhanced to support multi-radio access technology(RAT) features for NR and LTE Dual Connectivity (DC), potentially newservices (IoT or other 5G services), and features such as networkslicing (where, for example, different slices and CN functions mayrequire a different CN design), on demand activation of mobilityreference signals, new multi-connectivity solutions, potentially newuser plane/control plane splits in the CN, support for a new connecteddormant state, etc.

FIG. 2 shows the same logical architecture as FIG. 1, but now alsoincludes an example of an internal eNB architecture, including possibleprotocols splits and mapping to different sites.

Following are features of the architecture discussed herein:

-   -   LTE and NR may share at least integrated higher radio interface        protocol layers (PDCP and RRC) as well as a common S1*        connection to packet core (EPC)        -   The usage of LTE or NR for 5G capable UEs can be transparent            to the EPC (if desired).    -   The RAN/CN functional split over S1* is based on the current        split used over S1.

Note, however that this does not exclude enhancements to the S1*compared to S1, e.g., to support new features such as network slicing.

-   -   The 5G network architecture supports flexible placement        (deployment) of CN (EPC) functionality per user/flow/network        slice    -   Centralization of PDCP/RRC is supported. The interface between        PDCP/RRC and lower layer entities need not be standardized        (although it can be), but can be proprietary (vendor-specific).        -   The radio interface is designed to support architecture            flexibility (allowing for multiple possible functional            deployments, e.g., centralized/distributed).        -   The architecture also supports fully distributed PDCP/RRC            (as is the case with LTE, today).    -   To support NR/LTE dual connectivity with centralized PDCP and        RRC, NR supports a split somewhere between the RRC/PDCP layers        and the Physical layer, e.g., at the PDCP layer. Flow control        may be implemented on X2*, supporting the split of PDCP and        Radio Link Control (RLC) in different nodes.    -   PDCP is split into a PDCP-C part, used for Signaling Radio        Bearers (SRBs), and PDCP-U part, used for User Radio Bearers        (URBs), which can be implemented and deployed in different        places.    -   The architecture supports Common Public Radio Interface        (CPRI)-based splits between a Radio Unit (RU) and a Baseband        Unit (BBU), but also other splits where some processing is moved        to the RU/Antenna in order to lower the required front-haul        bandwidth towards the BBU (e.g., when supporting very large        bandwidth, many antennas).

Note that despite the above discussion, alternative RAN/CN splits arepossible, while still maintaining many of the features and advantagesdescribed herein.

This section discusses the different UE states in NR and LTE, with focuson the UE sleep states, or “dormant” states. In LTE, two different sleepstates are supported:

-   -   ECM_IDLE/RRC_IDLE, where only the Core Network (CN) context is        stored in the UE. In this state, the UE has no context in the        RAN and is known on Tracking Area (or Tracking Area List) level.        (The RAN context is created again during transition to        RRC_CONNECTED.) Mobility is controlled by the UE, based on cell        reselection parameters provided by the network.    -   ECM_CONNECTED/RRC_CONNECTED with UE configured DRX. In this        state, the UE is known on the cell level and the network        controls the mobility (handovers).

Out of these two states, ECM_IDLE/RRC_IDLE is the primary UE sleep statein LTE for inactive terminals. RRC_CONNECTED with DRX is also used,however the UE is typically released to RRC_IDLE after X seconds ofinactivity (where X is configured by the operator and typically rangesfrom 10 to 61 seconds). Reasons why it may be undesirable to keep the UElonger in RRC_CONNECTED with DRX include limitations in eNB hardwarecapacity or software licenses, or other aspects such as slightly higherUE battery consumption or a desire to keep down the number of HandoverFailures.

Given that initiating data transmission from ECM_IDLE in LTE involvessignificantly more signaling compared to data transmission from“RRC_CONNECTED with DRX”, the “RRC_CONNECTED with DRX” state is enhancedin NR to become the primary sleep state. The enhancement includes addingsupport for UE-controlled mobility within a local area, thus avoidingthe need for the network to actively monitor the UE mobility. Note thatthis approach allows for the possibility that the LTE solution can befurther evolved to create a common RRC Connected sleep state for NR andLTE.

The following are features of this NR UE sleep state, which is referredto herein as RRC_CONNECTED DORMANT (or RRC DORMANT for short):

-   -   It supports DRX (from milliseconds to hours).    -   It supports UE-controlled mobility, e.g., the UE may move around        in a Tracking RAN Area (TRA) or TRA list without notifying the        network (TRA (lists) span across LTE and NR).    -   Transition to and from this state is fast and lightweight        (depending on the scenario, whether optimized for energy saving        or fast access performance), e.g., as enabled by storing and        resuming the RAN context (RRC) in the UE and in the network.

When it comes to detailed solutions how this RRC DORMANT state issupported, there are different options based on different level of CNinvolvement. One option is as follows:

-   -   The CN is unaware of whether the UE is in RRC_CONNECTED DORMANT        or RRC_CONNECTED ACTIVE (described later), meaning the S1*        connection is always active when UE is in RRC_CONNECTED,        regardless of sub state.    -   A UE in RRC DORMANT is allowed to move around within a TRA or        TRA list without notifying the network.        -   Paging is triggered by the eNB when a packet arrives over            S1*. The MME may assist the eNB by forwarding page messages            when there is no X2* connectivity to all the eNBs of the            paging area.        -   When the UE contacts the network from RRC DORMANT in a RAN            node that does not have the UE context, the RAN node tries            to fetch the UE context from the RAN node storing the            context. If this is successful, the procedure looks like an            LTE X2 handover in the CN. If the fetch fails, the UE            context is re-built from the CN.    -   The area that the UE is allowed to move around without notifying        the network may comprise a set of Tracking RAN Areas, and covers        both LTE and NR RAT, thus avoiding the need to signal when        switching RAT in RRC DORMANT.

In addition to the RRC DORMANT state (optimized for power saving), thereis an RRC_CONNECTED ACTIVE (RRC ACTIVE) state used for actual datatransmission. This state is optimized for data transmissions, but allowsthe UE to micro-sleep, thanks to DRX configuration, for scenarios whenno data is transmitted but a very quick access is desired. This may bereferred to as monitoring configuration within the RRC ACTIVE state. Inthis state, the UE cell or beam level mobility is controlled and knownby the network.

Given a tight integration between NR and LTE, the desire to have a RANcontrolled sleep state in NR drives requirements to also support aRAN-controlled sleep state in LTE for NR/LTE capable UEs. The reason forthis is that to support tight NR and LTE integration, a common S1*connection is desirable for LTE and NR. If a RAN-controlled sleep stateis introduced on the NR side, it would be very beneficial to havesimilar sleep state on the LTE side, also with an active S1* connection,so that the sleeping UE can move between NR and LTE without performingsignaling to setup and tear down the S1* connection. This type ofinter-RAT re-selection between LTE and NR may be quite common,especially during early deployments of NR. Accordingly, a commonRAN-based sleep state called RRC_CONNECTED DORMANT should be introducedin LTE. The UE behavior in this state is similar to what is defined forLTE RRC suspend/resume, however the paging is done by the RAN and not bythe CN, since the S1* connection is not torn down when RRC is suspended.

Similarly, a common RRC_CONNECTED ACTIVE state between NR and LTE isdesirable. This state is characterized in that the NR/LTE capable UE isactive in either NR or LTE or both. Whether the UE is active in NR orLTE or both is a configuration aspect within the RRC ACTIVE state, andthese conditions need not be regarded as different sub states, since theUE behavior is similar regardless which RAT is active. To give oneexample, in the case only one of the links is active, regardless ofwhich link, the UE is configured to transmit data in one and to performmeasurements in another one for dual-connectivity and mobility purposes.

FIG. 3 shows the UE states in an LTE/NR system where LTE supports thecommon RRC_CONNECTED ACTIVE and RRC_CONNECTED DORMANT states discussedabove. These states are described further below.

Detached (Non RRC configured)

-   -   EMM_DETACHED (or EMM_NULL) state defined in Evolved Packet        Subsystem (EPS) when the UE is turned off or has not yet        attached to the system.    -   In this state the UE does not have any Internet Protocol (IP)        address and is not reachable from the network.    -   Same EPS state is valid for both NR and LTE accesses.        ECM/RRC_IDLE    -   This is similar to the current ECM_IDLE state in LTE.        -   This state may be optional.        -   In the event this state is kept, it is desirable for the            paging cycles and Tracking RAN Areas to be aligned between            RAN-based paging in RRC DORMANT and CN-based paging in            ECM_IDLE, since then the UE could listen to both CN- and            RAN-based paging making it possible to recover the UE if the            RAN based context is lost.            RRC_CONNECTED ACTIVE (RRC state)    -   UE is RRC-configured, e.g., it has one RRC connection, one S1*        connection and one RAN context (including a security context),        where these may be valid for both LTE and NR in the case of        dual-radio UEs.    -   In this state it is possible, depending on UE capabilities, to        transmit and receive data from/to NR or LTE or both (RRC        configurable).    -   In this state, the UE is configured with at least an LTE Serving        Cell or an NR serving beam and can quickly set up dual        connectivity between both NR and LTE when needed. The UE        monitors downlink scheduling channels of at least one RAT and        can access the system via for instance scheduling requests sent        in the uplink.    -   Network controlled beam/node mobility: UE performs neighbouring        beam/node measurements and measurement reports. In NR, the        mobility is primarily based on NR signals such as TSS/MRSs and        in LTE, Primary Synchronization Sequence (PSS)/Secondary        Synchronization Sequence (SSS)/CRS is used. NR/LTE knows the        best beam (or best beam set) of the UE and its best LTE cell(s).    -   The UE may acquire system information via a Signature Sequence        Index (SSI) and corresponding Access Information Table (AIT),        for example, and/or via NR dedicated signaling or via LTE system        information acquisition procedure.    -   UE can be DRX configured in both LTE and NR to allow        micro-sleeps (in NR sometimes referred as beam tracking or        monitoring mode). Most likely the DRX is coordinated between        RATs for UEs active in both RATs.    -   The UE can be configured to perform measurements on a non-active        RAT which can be used to setup dual connectivity, for mobility        purposes or just use as a fallback if the coverage of the active        RAT is lost.        RRC_CONNECTED DORMANT (RRC state)    -   UE is RRC-configured, e.g., the UE has one RRC connection and        one RAN context regardless of the access.    -   UE can be monitoring NR, LTE, or both, depending on coverage or        configuration. RRC connection re-activation (to enter RRC        ACTIVE) can be either via NR or LTE.    -   UE-controlled mobility is supported. This can be cell        re-selection in the case of only LTE coverage or NR Tracking RAN        Area selection in the case of NR-only coverage. Alternatively,        this can be a jointly optimized cell/area reselection for        overlapping NR/LTE coverage.    -   UE-specific DRX may be configured by RAN. DRX is largely used in        this state to allow different power saving cycles. The cycles        can be independently configured per RAT, however some        coordination might be required to ensure good battery life and        high paging success rate. Since the NR signals have configurable        periodicity there are methods that allow the UE to identify the        changes and adapt its DRX cycles.    -   UE may acquire system information via SSI/AIT in NR or via LTE.        UE monitors NR common channels (e.g., NR paging channel) to        detect incoming calls/data, AIT/SSI changes, Earthquake Tsunami        Warning System (ETWS) notification and Commercial Mobile Alert        System (CMAS) notification. UE can request system information        via a previously configured Random Access channel (RACH).

Several different types of measurements and/or signals are measured inNR, e.g., MRS, SSIs, Tracking RAN Areas Signals (TRAS), etc. Mobilityevents and procedures thus need to be addressed for NR.

The RRC Connection Reconfiguration message should be able to configureboth the NR measurements and the existing LTE measurements for thesingle RRC option. The measurement configuration should include thepossibility to configure the UE to measure for NR/LTE coverage e.g., toinitiate DC setup or inter-RAT handover (as in the legacy).

There are two different measurement reporting mechanisms for NR, non-RRCbased reporting, where the UE indicates the best of a set of candidatedownlink beams through a preconfigured uplink synchronization signal(USS) sequence; and RRC-based reporting, which is similar in somerespects to the event-triggered LTE measurement reporting. These twomeasurement reporting mechanisms are preferably deployed in parallel andused selectively, e.g., depending on the UE's mobility state.

System information as known from previous releases of the LTE standardsconsists of very different types of information, access information,node-specific information, system-wide information, public warningsystem (PWS) information, etc. Delivery of this wide range ofinformation does not use the same realization in NR. In a system withhigh-gain beamforming, the cost of providing large amount of data inbroadcast manner may be costly compared to point to point distributionin a dedicated beam with high link gain.

The paging solution for NR utilizes one or both of two channels: aPaging Indication Channel (PICH) and a Paging Message Channel (PMCH).The paging indication may contain one or more of the following: a pagingflag, warning/alert flag, identifier (ID) list, and resource allocation.PMCH may optionally be transmitted after the PICH. When the PMCH messageis sent, it may contain one or more of the following contents: ID list,and warning/alert message. Warning and broadcast messages are preferablyto be transmitted over the PMCH (and not in the AIT). To allow tightintegration with LTE, paging configuration (and so DRX configuration)may be Single-Frequency Network (SFN)-based.

To support paging functionality, tracking RAN areas are configured atthe UE. A tracking RAN area (TRA) is defined by a set of nodestransmitting the same tracking RAN area signal (TRAS). This signalcontains the Tracking RAN Area Code as well as the SFN.

Each TRA may have a specific paging and TRAS configuration which isprovided to the UE via dedicated signaling, e.g., via a TRA UpdateResponse or RRC Reconfiguration message. The TRA Update Response may,furthermore, contain paging messages.

A number of different reference signals are provided in NR, for channelestimation and mobility. Both the presence of the reference signals aswell as the measurement reports are controlled by the scheduler. Thepresence of signals can be dynamically or semi-persistently signaled toone or a group of users.

Also, reference signals for active mode mobility (MRS) can bedynamically scheduled. A UE is then assigned with a search space formobility transmissions. Observe that this search space is potentiallymonitored by one or more UEs and/or transmitted from one or moretransmission points.

Scheduled reference signal transmissions (such as MRS) contain a locallyunique (at least within the search space) measurement identity in thedata message, and reuse some or multiple of the pilots in thetransmission both for demodulation and measurement purposes, implyingthat it is a self-contained message.

NR uses OFDM as modulation scheme in both uplink and downlink, possiblyalso including a low peak-to-average power ratio (PAPR) mode (e.g.,discrete Fourier transform-spread OFDM, or DFTS-OFDM) forenergy-efficient low-PAPR operation and Filtered/Windowed OFDM forfrequency-domain mixing of numerologies. Note that a “numerology,” asthat term is used herein, refers to a particular combination of OFDMsubcarrier bandwidth, cyclic prefix length, and subframe length. Theterm subcarrier bandwidth, which refers to the bandwidth occupied by asingle subcarrier, is directly related to, and is sometimes usedinterchangeably, with subcarrier spacing.

The modulation scheme of NR is cyclic-prefix OFDM, both for uplink anddownlink, which enables a more symmetric link design. Given the largeoperating range of NR, sub-1 GHz to 100 GHz, multiple numerologies maybe supported for the different frequency regions. OFDM is a good choicefor NR, since it combines very favorably with multi-antenna schemes,another significant component in NR. In OFDM, each symbol block is verywell localized in time, which makes OFDM also very attractive for shorttransmission bursts, important for various MTC applications. OFDM doesnot provide as good isolation between subcarriers as some filter-bankbased schemes do; however, windowing or sub band filtering providesufficient isolation between sub bands (e.g., not individual subcarriersbut collections of subcarriers), where needed.

For some use-cases, mixing of different OFDM numerologies is beneficial.Mixing of OFDM numerologies can either be done in time-domain orfrequency domain. For mixing of MBB data and extremely latency-criticalMTC data on the same carrier, frequency-domain mixing of OFDMnumerologies is beneficial. Frequency-domain mixing can be implementedusing Filtered/Windowed OFDM. FIG. 4(a) shows a block diagram ofFiltered/Windowed OFDM. In this example, the upper branch uses narrow(16.875 kHz) subcarriers 400-1100. The lower branch uses wide (67.5 kHz)subcarriers 280-410 which correspond to narrow subcarriers 1120-1640.FIG. 4(b) shows the mapping of upper and lower branches to thetime-frequency plane. During the time duration of the large Inverse FastFourier Transform (IFFT) (2048 samples), four small IFFTs (512 samples)are performed.

In Filtered OFDM, sub bands are filtered to reduce interference towardsother sub bands. In Windowed OFDM, beginning and end of OFDM symbols aremultiplied with a smooth time-domain window (regular OFDM uses arectangular window spanning the length of an OFDM symbol includingcyclic prefix) reducing discontinuities at symbol transitions and thusimprove spectrum roll off. This is shown in FIG. 5, which illustrateshow the beginning and end of an OFDM symbol are multiplied by a smoothtime-domain window.

In the example frequency-domain mixing of OFDM numerologies shown inFIG. 4, the lower branch uses numerology with four times as widesubcarriers as the upper branch, e.g., 16.875 kHz and 67.5 kHz for theupper and lower branch, respectively. In this example, both branches usethe same clock rate after IFFT processing and can directly be added.However, in a practical realization this may not be the case; especiallyif one of the numerologies spans a much narrower bandwidth than theother processing at a lower sampling rate is preferable.

While filtered OFDM is possible, windowed OFDM is preferred due to itsgreater flexibility.

Sub band filtering or windowing (both at the transmitter and thereceiver) and guard bands are desirable to suppress inter-subcarrierinterference, since subcarriers of different numerologies are notorthogonal to each other. In addition to sub band filtering orwindowing, filtering across the transmission bandwidth is alsodesirable, to fulfill the desired out-of-band emission requirements. Aguard band of 12 narrowband subcarriers enables an SNR of 20+ dB on allsubcarriers, while a guard band of 72 narrowband subcarriers allows anSNR of 35+ dB on all subcarriers. To avoid unnecessary guard bandlosses, Filtered/Windowed OFDM may be limited to two contiguous blocksof different numerologies. To the extent that Filtered/Windowed OFDM issupported by the NR standard, every NR device—even a device onlysupporting a single numerology—should support transmit and receivefiltering/windowing since it could operate on an NR carrier operatingwith mixed numerologies (given the low complexity of windowing it isreasonable to assume that every UE can implement windowing). A networknode on the other hand, needs only to support Filtered/Windowed OFDM ifit supports use case mixes requiring frequency-domain mixing ofnumerologies. Note that detailed specifications of the windowing or subband filtering are not needed, but rather performance requirements totest the chosen implementation. Sub band filtering and windowing canalso be mixed on transmitter and receiver.

OFDM may also include a low-PAPR mode such as DFTS-OFDM. OFDM is used tomaximize performance while the low-PAPR mode might be used in noderealizations (both eNB and UE) where low peak to average power ratio(PAPR) of the waveform is important from a hardware perspective, e.g.,at very high frequencies.

At the physical layer, the minimum transmission unit is a subframe.Longer transmissions can be realized by subframe aggregation. Thisconcept enables a variable TTI, for a given transmission the TTIcorresponds to the length of the subframe or to the length of thesubframe aggregate in case of subframe aggregation.

Three subcarrier bandwidths are defined to cover the operating rangefrom below 1 GHz to 100 GHz and the large use case space.

NR supports both frequency-division duplexing (FDD) and dynamictime-division duplexing (TDD) modes. Even though not relevant for thefirst releases of NR, the concept is extendable to full duplex,especially at the base station, as full duplex technology becomes moremature.

The NR physical layer as described herein has no frames but onlysubframes. It is possible that the concept of frames can be introducedlater. Two basic subframe types, one for uplink and one for downlink,are defined. These subframe types are identical for both FDD and TDD.FIG. 6 depicts the basic subframe types, where T_(sf) is the subframeduration. T_(DL) and T_(UL) are the active transmission durations indownlink and uplink, respectively. A subframe consists of N_(symb) OFDMsymbols, but not all symbols in a subframe are always used for activetransmission. Transmission in a downlink subframe starts at thebeginning of the subframe and can extend from 0 up to at most N_(symb)OFDM symbols (later start of a transmission in a downlink subframe forlisten-before-talk operation is also possible). Transmission in anuplink subframe stops at the end of the subframe and can extend from 0up to at most N_(symb) OFDM symbols. The gaps—if present—are used in TDDfor transmission in the reverse direction within a subframe, asexplained below.

The duration of a single subframe is very short. Depending on thenumerology, the duration may be a few hundred μs or even less than 100μs, in the extreme case even less than 10 μs. Very short subframes areimportant for Critical Machine-Type Communication (C-MTC) devicesrequiring short latency, and such devices typically check for controlsignaling transmitted at the beginning of every downlink subframe. Giventhe latency critical nature, the transmission itself can also be veryshort, e.g., a single subframe.

For MBB devices, extremely short subframes are typically not needed. Itis therefore possible to aggregate multiple subframes and schedule thesubframe aggregate using a single control channel.

It is well known that robustness of an OFDM system towards phase noiseand Doppler shift increases with subcarrier bandwidth. However, widersubcarriers imply shorter symbol durations which—together with aconstant cyclic prefix length per symbol—result in higher overhead. Thecyclic prefix should match the delay spread and is thus given by thedeployment. The required cyclic prefix (in μs) is independent of thesubcarrier bandwidth. The “ideal” subcarrier bandwidth keeps the cyclicprefix overhead as low as possible but is wide enough to providesufficient robustness towards Doppler and phase noise. Since the effectof both Doppler and phase noise increase with carrier frequency therequired subcarrier bandwidth in an OFDM system increases with highercarrier frequency.

Considering the wide operating range of below 1 GHz to 100 GHz it isimpossible to use the same subcarrier bandwidth for the completefrequency range and keep a reasonable overhead. Instead, threesubcarrier bandwidths span the carrier frequency range from below 1 to100 GHz.

To enable subframe durations of a few 100 μs using LTE numerology (forLTE frequencies), one subframe would have to be defined as a few OFDMsymbols. However, in LTE, OFDM symbol durations including cyclic prefixvary (the first OFDM symbol in a slot has a slightly larger cyclicprefix) which would lead to varying subframe durations. (Varyingsubframe durations are in practice likely not a significant problem andcould be handled. In LTE, the varying cyclic prefix length leads tosomewhat more complicated frequency error estimators.) Alternatively, asubframe could be defined as an LTE slot, leading to subframe durationsof 500 μs. This, however is considered too long.

Therefore, even for LTE frequencies a new numerology is describedherein. The numerology is close to the LTE numerology, to enable thesame deployments as LTE, but provides subframes of 250 μs. Thesubcarrier bandwidth is 16.875 kHz. Based on this subcarrier bandwidthseveral other numerologies are derived: 67.5 kHz for around 6 to 30/40GHz or dense deployments (even at lower frequencies) and 540 kHz for thevery high frequencies. Table 1 lists the most important parameters ofthese numerologies, e.g., f_(s): Clock frequency, N_(symb): OFDM symbolsper subframe, N_(sf): samples per subframe, N_(ofdm): Fast FourierTransform (FFT) size, N_(cp): cyclic prefix length in samples, T_(sf):subframe duration, T_(ofdm): OFDM symbol duration (excluding cyclicprefix), and T_(cp): cyclic prefix duration). Table 1 is based on an FFTsize of 4096 and a clock frequency of 34.56 MHz to allow the covering oflarge carrier bandwidths.

The proposed numerologies are not based on the LTE clock frequency(30.72 MHz) but on 16.875/15·30.72 MHz=9/8·30.72 MHz=9·3.84 MHz=34.56MHz. This new clock relates via a (fractional) integer relation to bothLTE and Wideband Code-Division Multiple-Access (WCDMA) clocks and canthus be derived from them.

TABLE 1 Subcarrier bandwidth 16.875 kHz, normal cyclic prefix 16.875kHz, 67.5 kHz, 67.5 kHz, long 540 kHz, (CP) long CP normal CP CP normalCP Main scenario <~6 GHz <~6 GHz ~6 to 30-40 GHz Low delay in >30-40 GHzSFN or wide-area transm. dense depl. deployments f_(s) in MHz 69.12 = 2× 34.56 276.48 = 2 × 138.24 2212 = 2 × 1105.92 N_(symb) 4 3 4 7 4(larger number is possible) N_(sf) 17280 17280 17280 34560 17280N_(ofdm) 4096 4096 4096 4096 4096 N_(cp) 224 1664 224 4 × 848, 3 × 832224 CP overhead in % 5.5 40.6 5.5 20.5 5.5 T_(sf) in μs 250 250 62.5 1257.81 T_(ofdm) in μs 59.26 59.26 14.82 14.82 1.85 T_(cp) in μs 3.24 24.070.81 3.01 0.10 T_(ofdm) + T_(cp) in 62.5 83.33 15.625 17.86 1.95 μs Maxcarrier 60 60 250 250 2000 band- width in MHz

Note that numerologies for implementations may vary from those listed inTable 1. In particular, numerologies with long cyclic prefixes may beadjusted.

Table 1 shows that OFDM symbol duration and subframe duration decreasewith subcarrier bandwidth, making numerologies with wider subcarrierssuitable for low-latency application. The cyclic prefix length alsodecreases with subcarrier bandwidth, limiting the wider subcarrierconfigurations to dense deployments. This can be compensated by longcyclic prefix configuration, at the price of increased overhead. Inother words, shorter subframes and thus latencies are more efficientlyavailable in small cells than in large cells. In practice, however, itis expected that many latency critical applications deployed in the widearea (and thus require a cyclic prefix larger than 1 μs) don't requiresubframe durations smaller than 250 μs. In the rare cases where widearea deployments require smaller subframe durations, 67.5 kHz subcarrierbandwidth—with long cyclic prefix if needed—can be used. The 540 kHznumerology provides even shorter subframes.

The maximum channel bandwidths of the different numerologies are,approximately, 60 MHz, 240 MHz, and 2 GHz for 16.875 kHz, 67.5 kHz, and540 kHz numerology, respectively (assuming an FFT size of 4096). Widerbandwidths can be achieved with carrier aggregation.

Mixing of different numerologies on the same carrier is possible, usingFiltered/Windowed OFDM. One of the motivations is to achieve lowerlatency on a part of the carrier. Mixing of numerologies on a TDDcarrier should obey the half-duplex nature of TDD—simultaneoustransmission and reception capability of a transceiver cannot beassumed. The most frequent duplex switching in TDD is thus limited bythe “slowest” numerology among the simultaneously used ones. Onepossibility is to enable duplex switching on the “fastest” numerologysubframe basis when needed and accept losing currently ongoingtransmission in the reverse link.

Signature sequences (SS), as discussed below, are used to indicate anentry in AIT and to establish some level of subframe synchronization forat least random access preamble transmission. SS are constructed in asimilar way as the synchronization signal in LTE by concatenation of aprimary signature sequence and a secondary signature sequence.

The combination of time and frequency synchronization signal (TSS) andbeam reference signal (BRS) is used to obtain time/frequency/beamsynchronization after initial synchronization and access by SS andPhysical Random Access Channel (PRACH). This combined signal is alsoreferred to as MRS (mobility reference signal) and is used for handover(between nodes and beams), transitions from dormant to active states(e.g., from RRC_CONNECTED DORMANT to RRC_CONNECTED ACTIVE, as discussedabove), mobility, beam tracking and refinement, etc.

The MRS is constructed by concatenating TSS and BRS such that MRS istransmitted within a single DFT-precoded OFDM symbol.

Channel state information reference signals (CSI-RS) are transmitted indownlink and are primarily intended to be used by UEs to acquire channelstate information (CSI). CSI-RS are grouped into sub-groups according tothe possible reporting rank of the UE measurement. Each sub-group ofCSI-RS represents a set of orthogonal reference signals.

Positioning reference signals (PRS) aid positioning. Already existingreference signals should be reused for PRS purposes. On top of that—ifrequired—modifications and additions can be done to improve positioningperformance.

TABLE 2 Downlink reference and synchronization signals in NR SignalPurpose Signature sequence (SS) Used to synchronize time and frequencyfor random access. Provides index to AIT table. Mobility and accessreference Concatenation of one TSS and one BRS Signal (MRS) Time andfrequency Used to synchronize time (OFDM symbol timing) and coarsesynchronization signal (TSS) frequency offset estimation in a beam. Beamreference signal (BRS) Used for measurements on beam candidates toenable active mode mobility. Also used for frame and subframe timing.Demodulation reference signal Demodulation reference signals for PDCCH(DMRS) for PDCCH Channel state information Used for channel statemeasurements to aid rank and reference signal (CSI-RS) Modulation andCoding Scheme (MCS) selection. Positioning reference signal To aidpositioning. (PRS)

Basic functions of the signature sequence (SS) are one or more of:

-   -   to obtain the SSI, which is used to identify the relevant entry        in AIT;    -   to provide coarse frequency and time synchronizations for the        following initial random access and relative AIT allocation;    -   to provide a reference signal for initial layer selection (to        select which SS transmission point for a UE to connect, based on        the path-loss experienced by SS's);    -   to provide a reference signal for open-loop power control of the        initial PRACH transmission; and    -   to provide a coarse timing reference used for assisting the UE        in inter-frequency measurements and also possible beam finding        procedure. The current assumption is that SS transmissions are        synchronized within a ±5 ms uncertainty window unless explicitly        indicated otherwise. The period of SS is supposed to be in the        order of 100 ms, which however may be varied, depending on the        scenarios.

It is noted that the number of the candidate sequences needs to be largeenough to indicate any entry in AIT. Taking the terminal detectioncomplexity into account, the number of SS sequences is 2¹²,corresponding to 12 bits for reuse 1 of the sequences, or less if lessaggressive sequence reuse is required. Note that the number of bits tobe carried depends on requirements. If the number of bits increasesbeyond what can be carried by sequence modulation, a variation of the SSformat is desirable. In this case, one code-word containing the extrabits beyond what the sequences can carry can be appended. This block,following an SS transmission, is named SS block (SSB). The content inthis block is flexible and contains the other relevant information bits,which need a periodicity in the order of 100 ms. For example, they canbe the “AIT pointer”, which indicates the time and band where theterminals can find the AIT and even the transmission format of AIT toavoid full blind detection.

The sequence design for SS can follow the TSS/BRS sequence design, sincethey would provide the coarse synchronization function before theinitial random access.

To support the massive analog beamforming, a fixed absolute timeduration, e.g., 1 millisecond, is reserved to sweep multiple analogbeams.

In the process of acquiring system access information (acquiring systeminformation and detecting a suitable SSI), the UE gets time andfrequency synchronized towards one or several nodes by using SS. Thelatter is achieved in the case of system access information transmittedsimultaneously from several nodes in an SFN (single frequency network)manner.

When the UE enters active mode, it targets to receive or transmit with ahigh data rate connection, in which it might need more accuratesynchronization and perhaps beamforming.

Here, the mobility and access reference signal (MRS) is used. A UE mightalso need to change which node it is connected to e.g., from a node usedto transmit system access information to another node capable ofbeamforming. Furthermore, the UE might also change carrier frequency ornumerology to higher sub-carrier spacing and shorter cyclic prefix whenmoving to certain operational modes in active mode.

The MRS is constructed in order to do time and frequency offsetestimations as well as estimation of best downlink transmitter andreceiver beams towards an “active mode access point”. Frequency accuracyand timing provided by MRS is probably not sufficient for high-ordermodulation reception and finer estimation may be based on demodulationreference signals (DMRS) embedded in Physical Data Channel (PDCH) and/orCSI-RS.

The MRS may be constructed by concatenating a time and frequencysynchronization signal (TSS) and a beam reference signal (BRS) in timeinto one OFDM symbol, as illustrated in FIG. 7. This construction can bedone as a DFT-precoded OFDM symbol with cyclic prefix. With both TSS andBRS in the same OFDM symbol, the transmitter can change its beamformingbetween each OFDM symbol. Compared to having separate OFDM symbols forTSS and BRS, the time required for scanning a set of beam directions isnow halved. Both TSS and BRS thus have shorter time durations ascompared to separate OFDM symbols for each of them. The cost for theseshorter TSS and BRS is reduced energy per signal and thus reducedcoverage, which can be compensated by increasing the bandwidthallocation, repeating the signal, or increasing the beamforming gain bymore narrow beams. Where mixed numerology is supported, the numerologyused for MRS is the same as that one used by the UE for which MRS arescheduled. In the event that multiple UEs within the same beam usedifferent numerologies, MRS cannot be shared and MRS should betransmitted separately for each numerology.

Different beamforming configurations can be used to transmit the MRS indifferent OFDM symbol, e.g., in each of the three symbols shown in FIG.7. The same MRS might also be repeated several times in the same beam inorder to support analog receiver beamforming. There are only one or fewTSS sequences, similar to PSS in LTE. The UE performs matched filteringwith the TSS sequence to obtain OFDM symbol timing estimation; TSSshould therefore possess good a-periodic auto-correlation properties.This sequence might be signaled by system information such thatdifferent AP (Access Points) can use different TSS sequences.

The MRS (as constructed by TSS+BRS) signal package is usable for allactive mode mobility-related operations: first-time beam finding,triggered beam mobility update in data transmission and monitoringmodes, and continuous mobility beam tracking. It may also be used forthe SS design.

The TSS sequence is identical in all OFDM symbols and beam directionstransmitted from a base station, while BRS uses different sequences indifferent OFDM symbols and beam directions. The reason for havingidentical TSS in all symbols is to reduce the number of TSS which a UEmust search in the quite computational complex OFDM symbolsynchronization. When the timing is found from TSS, the UE can continueto search within a set of BRS candidates in order to identify the OFDMsymbol within a subframe as well as best downlink beam. Best downlinkbeam can then be reported by USS.

One choice for such sequences is the Zadoff-Chu sequences as used forPSS in LTE release 8. However, these sequences are known to have largefalse correlation peaks for combined timing and frequency offsets.Another choice is differential coded Golay sequences, which are veryrobust against frequency errors and have small false correlation peaks.

The beam reference signal (BRS) is characterized by different sequencestransmitted in different transmitted beams and OFDM symbols. In thisway, a beam identity can be estimated in the UE for reporting to theaccess node.

An identification of OFDM symbol within the subframe is desirable if thetiming difference between SS and active mode transmissions is large.This might occur for numerologies with short OFDM symbols, largedistance between the node transmitting system access information and thenode in which the UE is supposed to transmit user data (in case thesenodes are different), or for unsynchronized networks. Thisidentification can be done if different BRS sequences are used fordifferent OFDM symbols. However, in order to reduce computationalcomplexity, the number of BRS sequences to search for should be low.Depending on the OFDM symbol index uncertainty, a different number ofBRS sequences may be considered in the blind detection of the UE.

The BRS can be a dedicated transmission to one UE or the same BRS mightbe configured for a group of UEs. A channel estimate from TSS can beused in a coherent detection of BRS.

CSI-RS are transmitted in downlink and are primarily intended to be usedby UEs to acquire channel state information (CSI) but can also serveother purposes. The CSI-RS may be used for one or more of (at least) thefollowing purposes:

-   -   Effective channel estimation at the UE: Frequency selective CSI        acquisition at the UE within a downlink beam, e.g., used for        Precoder Matrix Indicator (PMI) and rank reporting.    -   Discovery signal: Reference Signal Receive Power (RSRP)-type        measurement on a set of CSI-RS reference signals. Transmitted        with a time density according to large scale coherence time of        the relevant (downlink) channels.    -   Beam refinement and tracking: Get statistics about the downlink        channel and PMI reporting to support beam refinement and        tracking. PMI does not need to be frequency selective.        Transmitted with a time density according to large scale        coherence time of the relevant (downlink) channels.    -   For UE transmit beam-forming in uplink assuming reciprocity.    -   UE beam-scanning for analog receive beam-forming in downlink        (similar requirements to 1) or 3) depending on use-case).    -   To assist fine frequency/time-synchronization for demodulation.

In some cases, not all of the above estimation purposes needs to behandled by CSI-RS. For example, frequency offset estimation cansometimes be handled by downlink-DMRS, beam-discovery is sometimeshandled by BRS. Each CSI-RS transmission is scheduled and can be in thesame frequency resources as a PDCH downlink-transmission or in frequencyresources unrelated to the PDCH downlink-data transmissions. In general,no interdependence between CSI-RS in different transmissions can beassumed, and hence the UE should not do filtering in time. However, a UEcan be explicitly or implicitly configured to assume interdependencebetween CSI-RS, for example, to support time-filtering of CSI-RSmeasurements (e.g., in 2 above) and also interdependence to othertransmissions including PDCCH and PDCH. In general, all UE filteringshall be controlled by the network, including filtering of CSI in time,frequency and over diversity branches. In some transmission formats,CSI-RS is situated in a separate OFDM symbol to better support analogbeam-forming both for the base station transmitter (TX) and the UEreceiver (RX). For example, to support UE analog beam-scanning (item 5above) the UE needs multiple CSI-RS transmissions to measure on in orderto scan multiple analog-beam candidates.

In LTE, the UE camps in a “cell”. Prior to camping, the UE performs acell selection which is based on measurements. Camping means that the UEtunes to the cell control channels and all the services are providedfrom a concrete cell and the UE monitors the control channels of aspecific cell.

In NR, different nodes may transmit different information. Some nodesmay transmit the SSI/AIT table, while others may not transmit SSI and/orAIT, for instance. Similarly, some nodes could transmit the trackinginformation while others may transmit paging messages. The notion ofcell becomes blurry in this context and, therefore, the concept of cellcamping is no longer suitable in NR.

The relevant signals the UE may monitor while in a dormant state or mode(e.g., the RRC_CONNECTED DORMANT state discussed above) are one or moreof:

-   -   SSI    -   Tracking RAN Area Signal—TRAS    -   Paging Indication Channel/Paging Message Channel.

NR camping is, therefore, related to the reception of a set of signals.The UE should camp on the “best” SSI, TRAS, and PICH/PMCH. NR camping(re-)selection rules for these signals are used, just as cell(re-)selection rules exist in LTE. However, since the degree offlexibility is higher, these rules may also be slightly morecomplicated.

Location information is desirable to assist the network to locate theUE. Solutions to provide location information using the SSI/AIT arepossible; however, at the cost of introducing certain constraints.Another solution is to use the SSI block. The SSI block could carry thecontent or part of the content described in the Tracking RAN Area SignalIndex (TRASI). The SSI block is independent of the SSI. Therefore, itcould qualify as an option to provide location information. Yet, anothersolution which provides a higher degree of flexibility is to introduce anew signal to carry such information. This signal is in this contextcalled Tracking RAN Area Signal, TRAS. The area in which this signal istransmitted is called Tracking RAN Area, TRA. A TRA may contain one ormore RAN nodes, as depicted in FIG. 8. The TRAS may be transmitted byall or a limited set of nodes within the TRA. This also means that thissignal and its configuration should preferably be common for all thenodes transmitting the TRAS within the given TRA, e.g., in terms of (atleast) roughly synchronized transmissions, to facilitate the proceduresfor the UE and aid it to reduce its energy consumption.

The Tracking RAN Area Signal (TRAS) comprises two components, a TrackingRAN Area Signal Synchronization (TRASS) and a Tracking RAN Area SignalIndex (TRASI).

In dormant mode, prior to each instance of reading the TRA info, the UEsare typically in a low-power DRX state and exhibit a considerable timingand frequency uncertainty. The TRA signal should therefore also beassociated with a sync field that allows the UE to obtain timing andfrequency synchronization for subsequent payload reception. To avoidduplicating synchronization support overhead in yet another signal,TRASI reception can use SSI for the purposes of synchronization indeployments where SSI and TRAS are transmitted from same nodes and areconfigured with a suitable period. In other deployments where the SSI isnot available for sync prior to reading TRASI, a separate sync signal(TRASS) is introduced for that purpose.

The SSI design has been optimized to provide UE synchronization. Sincethe synch requirements for TRA detection, not least the link qualityoperating point for the UE and the required ability to read the downlinkpayload information, are similar, we reuse the SS physical channeldesign and reserve one, or a small number, of the PSS+SSS sequencecombinations to be used as the TRA sync signal. The SS detectionprocedure at the UE may be reused for TRA synchronization. Since TRASSconstitutes a single predetermined sequence, or a small number of them,the UE search complexity is reduced.

Information about whether TRASS is configured by the network may besignaled to the UE, or the UE may detect it blindly.

The tracking area index is broadcasted. At least two components havebeen identified to be included in the Tracking RAN Area Signal Index(TRASI) payload:

-   -   Tracking RAN Area code. In LTE, a Tracking Area code has 16        bits. The same space range may be used for NR.    -   Timing information. As an example, a System Frame Number (SFN)        length of 16 bits may be used, which would allow a 10 minutes        DRX, given a radio frame length of 10 ms.

The payload is thus estimated as 20-40 bits. Since this number of bitsis impractical to encode into individual signature sequences, the TRAinformation is transmitted as coded information payload (TRASI) withassociated reference symbols (TRASS) to be used as phase reference.

The TRASI payload is transmitted using the downlink physical channelstructure:

-   -   Alternative 1 [preferred]: Use PDCCH (persistent scheduling).        The UE is configured with a set of 1 or more PDCCH resources to        monitor    -   Alternative 2: Use PDCH (persistent scheduling). The UE is        configured with a set of 1 or more PDCH resources to monitor    -   Alternative 3: Use PDCCH+PDCH (standard shared channel access).        The UE is configured with a set of 1 or more Paging Control        Channel (PCCH) resources to monitor, which in turn contain a        pointer to PDCH with the TRA info

The choice between PDCCH and PDCH should be based on whether reservingresources in one or the other channel imposes fewer schedulinglimitations for other signals. (For nomenclature purposes, the usedPDCCH/PDCH resources may be renamed as TRASI physical or logicalchannel.

TRASI encoding includes a Cyclic Redundancy Check (CRC) to reliablydetect the correct decoding at the UE.

The UE uses its standard SSI search/sync procedure to obtain sync forTRASI reception. The following sequence may be used to minimize the UEenergy consumption:

-   -   First look for TRASS    -   If TRASS not found, look for most recent SSI    -   If same SSI not found, continue to full SSI search

In some UE implementations, the receiver wake-up time, i.e., the periodsof time in which all or substantial parts of the receiver circuitry areactivated, is the dominant energy consumption factor, in which case fullsearch may always be performed.

If no TRASS is present but several SSIs are audible, the UE attemptsTRASI reception at all found SSI and/or TRASS timings, one of whichsucceeds. All SSIs are detected and corresponding TRASI detection isattempted during the same awake period, so no receiver overhead isintroduced.

If a relatively loose sync with a known tolerance within a TRA isprovided, a UE searches for TRAS-related time sync in the relevantvicinity of the current timing, plus the worst-case timing drift duringthe DRX. The UE RX waking time thus increases proportionally withincreased timing tolerance.

TRA configuration should be identical within the TRA. This means thatall the nodes which transmit the TRAS should use the same configuration.The reason behind this is due to the DRX configuration. A UE in dormantmode, such as the RRC_CONNECTED DORMANT state discussed above, wakes upfor a certain period of time. In that period of time, the UE is expectedto monitor and perform measurements as configured by the network (or asmandated by the standard).

TRA configuration is conveyed via dedicated signaling. AIT is not themost suitable option to convey this information. The TRA configurationcould be transmitted to the UE, for example, when the network commandsthe UE to move from an active Mode, such as RRC_CONNECTED ACTIVE stateto a dormant mode, such as RRC_CONNECTED DORMANT state, or when thenetwork transmits a TRA Update Response to the UE. TRA UpdateResponse—could also carry paging information (see FIG. 9). This could beespecially useful to minimize paging delays in situations when thenetwork is trying to locate a UE in TRA which the UE has already exited.To be able to support this type of functionality, the UE may need to addin the TRA Update some type of ID or other information to assist the newTRA or node to identify previous TRAs or nodes which could contain theUE context, paging messages or user data.

In FIG. 9, which illustrates a TRA update procedure, a UE moves from aTRA_A to a TRA_B which is not configured in its TRA list. When the UEhas exited the TRA_A, but not registered yet in TRA_B, the networkstarts sending paging indications over a certain node or set of nodes inTRA_A. The UE does not respond since it has exited the TRA_A and may notmonitor the TRAS_A any longer. When the UE performs a TRA Update, thenetwork provides the new TRA list and configuration, and may furtherinclude any paging indications which the UE could have been missed.

The less synchronized the network is, the higher the UE battery impactis. Keeping a tight synchronization across TRAs is therefore importantbut also challenging, especially in deployments with poor backhaul.

A few options are listed below:

-   -   All TRAs are loosely synchronized.    -   No synchronization across TRASs.    -   Sliding synchronization across neighbour nodes.    -   Loosely synchronized within the TRA & not synchronization among        TRASs.

FIG. 10 illustrates options of beam shapes for feedback-based solutionsin NR.

Transmitting in a beam implies that there is a directional, possiblynarrow, propagating stream of energy. The notion of a beam is thusclosely related to the spatial characteristics of the transmission. Toease the discussion, the beam concept is first explained. In particular,the notion of a high-rank beam is described.

Here, a beam is defined as a set of beam weight vectors, where each beamweight vector has a separate antenna port, and all the antenna portshave similar average spatial characteristics. All antenna ports of abeam thus cover the same geographical area. Note, however, that the fastfading characteristics of different antenna ports may be different. Oneantenna port is then mapped to one or several antenna elements, using apossibly dynamic mapping. The number of antenna ports of a beam is therank of the beam.

To illustrate the beam definition, take the most common example of arank-2 beam. Such a beam is realized using an antenna withcross-polarized elements, where all antenna elements with onepolarization are combined using one beam weight vector, and all antennaelements with the other polarization are combined using the same beamweight vector. Each beam weight vector has one antenna port, and sincethe same beam weight vector is used for the two antenna ports, the twobeam weight vectors together constitute one rank-2 beam. This can thenbe extended to beams of higher rank.

Note that high-rank beams may not work for the UE. Due to the irregularantenna element layout, the rich scattering at the UE and the fact thatthe UE antenna elements may have different characteristics, it is verychallenging to construct several beam weight vectors with similarspatial characteristics. Note that this does not preclude spatialmultiplexing in the uplink: this can be achieved using several rank-1beams.

It is very important to note that the beam shapes can be quite flexible.Hence, “beam-based transmission” is not the same as “fixed-beamtransmission”, although using a fixed grid of beams may be a suitableimplementation in many cases. The working assumption is that each beamhas between 1 and 8 ports, and each beam is associated with a CSI-RSwith a rank ranging from 1 to 8.

From UE's point of view, no major difference to element-based feedbackis foreseen other than the CSI-RS configuration; namely, that forbeam-based transmission, the CSI-RS allocations need to be moreflexible. Even though the configuration is flexible this does notpreclude that the UE may do filtering and interpolation, but this isunder strict network control.

In beam-based transmission, communication occurs through beams, wherethe number of beams may be much smaller than the number of antennaelements. Since the beams are still adjustable, the antenna system as awhole retains all its degrees of freedom. However, a single UE is notcapable of supporting all these of freedom using instantaneous feedback.Note that this is in contrast to element-based transmission, where theUE sees all the degrees of freedom of the antenna, and is capable ofreporting based on this knowledge.

From the network's point of view, multiple simultaneous beams can begenerated, either using analog beamforming or digital domain processing.It is assumed that as long as the formed beams are of similar width asthe angular spread of the channel, the overhead to maintain the UE beamassociations are reasonable: the best beam for any single UE does notthen vary with the fast fading. When the beam is narrower than theangular spread of the channel, the best beam for any single UE variesover time, leading to that the best beam association needs to befrequently updated. In some cases, the antenna patterns are fixed; seeFIG. 10, option 2. In some cases, the beams are adapted to the UEschannel characteristics; see FIG. 10, option 3, where user 2 with a richchannel receives data through a wide high-rank beam and theline-of-sight user 1 a narrow rank-2 beam.

Beam-based transmission is applicable in both FDD and TDD, for anyfrequency band, and antenna size.

Beam-based uplink reception implies that the baseband does not haveindividual access to all antenna elements. In this case, some sort ofspatial preprocessing or preliminary beamforming may be applied. Thispreprocessing can be performed in the analog domain, in the digitaldomain, or in a hybrid of the two. In general, the spatial preprocessingcan be quite flexible. It needs to be time-varying to adapt the coveragearea of the antenna to where the users are.

Both phase and amplitude tapering can be considered.

In the downlink, the individual antenna elements are never exposed tothe UE. The UE only sees a number of linear combinations of the signalstransmitted from different antenna elements. The number of linearcombinations that is exposed is determined by the rank of thetransmission. Data is received at the UE through such a linearcombination (the beam) and downlink quality is measured and reported perbeam.

One possible scenario is that the UE is equipped with multiple arrays,each array consisting of a (small) number of elements. The differentarrays cover different spatial directions. The array can be configuredto have different angular coverage (pointing direction and beam width).

The UE transmits reference signals (RSs) through a number of beams,either sequentially or simultaneously. Sequential transmission can beused also with analog TX beamforming, and the detection at the eNB iseasier. On the other hand, if RSs are transmitted over several beams inparallel, more beams can be probed in a shorter time. The RS is probablyReciprocity Refernce Signal (RRS), as different RSs should betransmitted through different beams, so that the eNB can identify eachtransmission. The shape of each beam is decided by the UE, but thenumber of beams is between the UE and the eNB. The eNB measures thequality of each received RS, and determines the most suitable UEtransmit beam. The decision is then sent to the UE over dPDCH, togetherwith a channel quality information (CQI) value and a scheduling grant.

As mentioned above, it may not be possible to form a high-rank beam atthe UE. To enable uplink multiple-input multiple-output (MIMO), severalrank-1 beams may be used.

At the eNB, beam-based transmission typically means that the number ofelements seen by the baseband is much lower than the number of elementsused to form the beams. This implies that the (angular) coverage ofsimultaneous individual beams is less than by the elements.

At the UE, beam-based transmission for feedback purposes may be used toimprove link budget for RSs but perhaps not to reduce the angularcoverage, such that the number of beams may still be equal to the numberof elements.

For an ongoing transmission, there is a possibility to reduce theangular coverage, as is done on the eNB side, but this may imply that,after some time, the channel is not fully utilized. To prevent this,sounding, with wide or possibly full angular coverage, is required.

For NR, the active mobility management solution described above isconfigured to manage mobility between beams, as opposed to thetraditional cell mobility in Long-Term Evolution (LTE). Beam-orientedtransmission and mobility introduce numerous features that differ fromLTE cell mobility. Using large planar antenna arrays at access nodes,with the number of elements in the hundreds, fairly regulargrid-of-beams coverage patterns with hundreds of candidate beams pernode may be created. The beam widths of the individual beams inelevation and azimuth are determined by the number of element rows andcolumns in the array.

As illustrated in simulation studies, the coverage area of an individualbeam from a large planar array may be small, down to the order of sometens of meters in width. Channel quality degradation outside the currentserving beam area is rapid, which may necessitate frequent beamswitching to reap the full potential of the antenna array with lowoverhead. Static mobility signals in all beams are not feasible, so MRSneed to be turned on only in relevant beams and only when needed. Therelevant beams are selected based on the UE position and prior beamcoverage statistics for the different candidate beams, based on aself-organizing network (SON) database. The SON data may also be used totrigger mobility measurement sessions when the serving beam qualitydegrades, without the need for continuous neighbour beam qualitycomparisons.

Evaluations indicate also that sudden beam loss is possible due toshadow fading, e.g., when turning a street corner. The active modemobility (AMM) solution includes features that assist in avoiding orrapidly recovering from a sudden link quality reduction or out-of-synchcondition.

The AMM solution includes both lower-layer procedures (mobility trigger,measurements, beam selection, RS design, and robustness) and RRC topics(beam identity management, inter-node handover, and other higher-layeraspects). The AMM solution supports both beam switches within one nodeand between different nodes using primarily measurements on MRS. Notethat the procedures described in this section can be used to changebeams within one node using measurements on CSI-RS. Or to be moreprecise: beam-switches using CSI-RS can be used for cases when the dataplane does not have to be re-routed, and no resynchronization needs tobe done. On these cases, the CSI-RS-based procedure is much leaner, andis also completely transparent to the UE.

Furthermore, the AMM solution distinguishes between link beams andmobility beams. Link beams are the beams used for data transmission,whereas mobility beams are used for mobility purposes.

The NR system should provide seamless service experience to users thatare moving, and is designed to support seamless mobility with minimaluse of resources. As mentioned above, there is a dormant mode (referredto above as RRC_CONNECTED DORMANT state) and an active mode (referred toabove as RRC_CONNECTED ACTIVE state) in NR, which means that themobility includes the dormant mode mobility and active mode mobility.The mobility in dormant mode (location update and paging) is discussedin detail below. In this section, only the intra-NR active mode mobilityis treated. A description of reference signals used for mobilityprocedures was presented above.

There are some specific needs that the mobility solution shouldpreferably fulfill, which include one or more of:

-   -   The mobility solutions shall support movement between beams        without any packet loss. (In LTE, packet forwarding is used—some        temporary extra delay is OK but loss of packets is not.)    -   The mobility solution shall support multi-connectivity, where        coordination features usable for nodes connected both via        excellent backhaul (e.g., dedicated fiber) as well as via        relaxed backhaul (e.g., latency of 10 ms and above, wired,        wireless).    -   The mobility solutions should work for both analog beamforming        and digital beamforming.    -   Mobility and UE measurements shall work for both synchronized        and unsynchronized access nodes.    -   The mobility solutions shall support radio link failure        detection and recovery actions by the UE. The mobility solutions        shall support movement between NR and all existing RATs with a        tighter integration between NR and LTE with short inter-RAT        handover interruption time.

Desirable design principles for active mode mobility include one or moreof:

-   -   A mobility framework built of configurable functions shall be        used.    -   Mobility solutions shall have the flexibility that the downlink        and uplink mobility can be triggered and executed independent to        each other.    -   For active mode, mobility solutions shall be network controlled        as a general rule, network configured UE control can be used to        the extent there are proven large gains.    -   Mobility-related signalling shall follow the ultra-lean        principle. Preferably it shall occur on-demand, to minimize        measurement signal transmission. The signaling overhead and        measurement overhead related to mobility should be minimized.    -   The mobility solutions shall always maintain a good-enough link        between the terminal and the network (which is different from        “always be on the best”).    -   The mobility solutions should work independently of the        “transmission modes”.

Multi-antenna transmission already plays an important role for currentgenerations of mobile communication and takes on further importance inNR to provide high data rate coverage. The challenges facing active modemobility in NR are related to supporting the high-gain beam forming.When the link beams are relatively narrow, the mobility beams should betracking UEs with high accuracy to maintain good user experience andavoid link failure.

The downlink mobility concept of NR is beam-based. In deployments withlarge antenna arrays and many possible candidate beam configurations,all beams cannot transmit reference and measurement signals in analways-on, static manner. Instead, the connected access nodes select arelevant set of mobility beams to transmit when required. Each mobilitybeam carries a unique Mobility Reference signal (MRS). The UE is theninstructed to measure on each MRS and report to the system. From a UEpoint of view, this procedure is independent of on how many access nodesare involved. As a consequence, the UE does not have to care about whichaccess node is transmitting which beams; sometimes this is referred toas the UE being node-agnostic and the mobility being UE-centric. Formobility to work efficiently, the involved access nodes need to maintainbeam neighbour lists, exchange beam information, and coordinate MRSusage.

Tracking a moving UE is achieved by the UE measuring and reportingrelevant candidate beams' quality, whereby the system can select beamsfor data transmission based on the measurements and proprietarycriteria. The term beam switching is, in this context, used to describethe event when the access nodes update the parameters, e.g.,transmission point and direction of the beam. Thus, both intra- andinter-access node beam hand-overs can be seen as a beam switches. As aconsequence, hand-over in NR is executed between beams rather than cellsas in traditional cellular systems.

The beam type discussed in this section is mainly the mobility beam,which is the entity to update during mobility. Besides the mobilitybeam, there is also a ‘geo-fence’ beam which is introduced to easeinter-node mobility in some deployments.

The following sections describes downlink mobility: choosing whichbeam/node to use for downlink transmission. One section describesdownlink measurement-based mobility and one section describes uplinkmeasurement-based. So far, it is assumed that the same beam/node is usedfor uplink communication. However, in some cases, it can be advantageousto use different beams/nodes for downlink and uplink communication. Thisis called uplink/downlink decoupling. In that case, a separate proceduremay be used to select the best uplink beam/node. Uplink measurements areused to select the uplink beam/node, and the procedures described aboveare used with minimum changes.

Several detailed studies of mobility solution options have been carriedout, and all these formulations follow a common mobility framework,which can be summarized at a high level as in FIG. 11, which illustratesa generic active mode mobility (downlink measurement based) procedure.After it is decided to trigger a beam switch, a set of candidate beamsare selected for activation and measurement. These beams may originateboth in the serving access node and in potential target access nodes.Measurements are based on Mobility Reference Signal (MRS) transmissionsin mobility beams. The network decides the target beam after UE reportsthe result of the measurements to the network and optionally informs theUE of the selected target beam. (Alternatively, the UE may have beenproactively configured to autonomously select the candidate beam withthe best measurement result, and subsequently transmit the measurementreport to the target beam.) The procedure includes one or more of:

UE side:

-   -   Measurement configuration. UE receives the mobility        configuration from network about which MRSs to measure (or the        UE could also do a full blind search without a configured list),        when to measure, how to measure, and how to report. The        measurement configuration can be performed earlier (and        continuously updated.)    -   Measurement. UE performs mobility measurements after UE receives        measurement activation which is instructed to start measuring on        some or all of the entries in the measurement configuration.    -   Measurement report. UE sends mobility measurement reports to the        network    -   Mobility execution.        -   UE may receive a request to transmit USS in the uplink for            timing advance (TA) measurement and send the USS. The            requirement to send USS can be part of measurement            configuration.        -   UE may receive a command (reconfiguration) to perform beam            switch, which may include a new beam ID and a TA adjust            command. The switch command can also be first informed, and            TA can be measured and adjusted in target node.        -   Or, if the downlink sync and uplink TA remain valid, and the            additional configuration (new DMRS, security, etc.) is not            required or can be informed via target node, the UE may not            receive a switch command.            Network side:    -   Measurement configuration. Network sends mobility measurement        configuration to UE.    -   Mobility trigger. Network determines whether to trigger beam        switching procedure.    -   Mobility measurement. Network decides to execute mobility        measurement procedure which includes:        -   Neighbour selection: Network selects candidate beams.        -   Measurement configuration. Network sends measurement            configuration to UE if it is not configured in step 1.        -   Measurement activation. Network activates MRS in relevant            beams and sends a measurement activation command to UE.        -   Measurement report. Network receives measurement report from            UE.    -   Mobility execution.        -   Network may send a USS request command (reconfiguration) to            UE to transmit USS for TA measurement.        -   The target node may measure the TA value and send the value            to the node communicating with the UE who will send TA            configuration to the UE.        -   Network may send beam switching (reconfiguration) command to            UE.

Network can send measurement configuration to UE either beforetriggering beam switching procedure (step 1) or after (during step 3).

The outlined sequence is configurable with suitable settings to serve asa common framework for all active mode mobility-related operations:first-time beam finding, triggered beam mobility update in datatransmission and monitoring modes, and continuous mobility beamtracking.

A configuration of the generic downlink active mode mobility procedurewhere the UE moves from Serving Access Node 1 (SAN1) to SAN2, as shownin FIG. 11, is described in the following section

The network may send a mobility measurement configuration to the UE.This configuration is transmitted in an RRC message and may containinformation related to measurement events—“what” (e.g., which MRSindices) to measure, “when” and “how” to measure (e.g., start time orcriterion and filtering duration), or “when” and “how” to send ameasurement report (e.g., report time slot, report best beam IDs or alsotheir powers, etc.). The list may be useful if only a small number ofMRS are turned on and can be measured on. But sending the list can beoptional for the Network, NW, and UE can perform measurements blindly,e.g., detecting all audible MRS signals. Another example ofconfigurability could be inter-node measurements where longer filteringmay be required to avoid ping-pong effects. For intra-node beammeasurements, a short filter is used.

A measurement configuration may be sent by the network at any time.Typically, once the UE receives the configuration, it starts performingmeasurements. However, this procedure could be further enhanced bytransmitting an activation command in the downlink control information(DCI) field. Thus, the RRC message would only configure the measurementbut may not necessary initiate the UE to start performing suchmeasurements.

The UE sends measurement reports based on the configuration provided bythe network. Measurement reports are typically RRC messages sent to thenetwork. However, in certain cases, some type of reports could be sentover MAC. For the Layer 3 based report, different number of beams can bereported concurrently, allowing to find the preferred beam in a shorttime, however it requires more signaling overhead, and it is not easy tointegrate beam switching with the scheduler. For Layer 2 basedreporting, there is less overhead, and it is easy to integrate withscheduler, however, a fixed maximum number of beam measurements can beconcurrently reported.

The MRS transmission and measurements are triggered based on theobserved link beam/node quality when data transmission is ongoing,mobility beam quality in the absence of data, or reports sent by the UE.Other triggers such as load balancing may also trigger mobilitymeasurement execution.

There are different trigger metrics and different conditions. The metricto reflect beam quality is either RSRP or SINR. The condition can be oneor more of:

-   -   a1) comparison to one absolute value    -   a2) comparison to multiple different relative values to a        reference table according to position    -   a3) comparison to values of other beams, or    -   a4) degradation rate of the link beam quality. Practical trigger        mechanisms that react to changes in the current quality metric        have also been demonstrated.

The observed beam can be one or more of the:

-   -   b1) current serving link beam (DMRS or CSI-RS),    -   b2) current serving link beam plus its ‘sector’ beam,    -   b3) current serving mobility beam (MRS).

The different types of switching (e.g., intra-node or inter-node) mayhave different thresholds. For example, when link quality is worse thanthreshold 1, intra-node beam switch is triggered. When link quality isworse than threshold 2, inter-node beam evaluation and switching istriggered. If excellent backhaul (e.g., dedicated fiber) is present andthere is no problem with ping-pong effects, both intra-node andinter-node can use the same parameters.

When the network decides that a serving beam/node identity need to bechanged/updated/modified, the network prepares the mobility procedure.This may imply some communication with other nodes in the network.

There are several options for reporting the MRS measurement results tothe network:

-   -   c1) If the UE reports all measurements to the serving node, the        serving node determines the node to switch to and signals to the        UE. This approach relies on the existing serving link for all        signaling during the mobility procedure. TA towards the new        serving beam is estimated in conjunction with the switch        command.    -   c2) If the UE reports the measurements back to the individual        nodes where the different MRS came from, the reporting itself        requires a previous USS transmission and TA estimation—it is        then seen as part of the measurement procedure. Once the Network        has decided the new serving node and signaled to the UE, the UE        uses the already available TA towards the new serving node. This        approach requires more uplink signaling, but removes the        critical dependence on the old serving link once the measurement        command has been issued.    -   c3) Similar to c2), but the UE reports all the measurements back        via the serving beam and via the best of the measured new beams.        Then, only one TA estimation procedure should be conducted.

Eventually, the network may request the UE to apply a new configuration.There may be situations in which a reconfiguration could be transparentfor the UE, e.g., in an intra-node beam switch. The reconfiguration thenhappens on the network side, a serving beam/node may be changed;however, the UE keeps the existing configuration. If a reconfigurationis needed, it can be configured before or after the switch.

In general, the MRS is only transmitted based on demand. The networkdecides which candidate beams, or neighbour beams, should be activated.Candidate beam selection can be based on, e.g., a beam relations lookuptable. This neighbourhood lookup table is indexed by either UE positionor radio fingerprint. The position can be the accurate position (e.g.,Global Positioning System (GPS) info) or an approximate position(current serving beam info). Creating and maintaining the neighbourhoodlookup tables is a generalization of the automatic neighbour relations(ANR) management process, handled by the SON functionality in thenetwork. The tables can be used both for providing trigger criteria toinitiate a measurement session towards a given UE and for determiningthe relevant candidate beams for measurements and a possible beamswitch. The beam in this lookup table can be either a normal mobilitybeam or a ‘sector’ beam. The neighbour beam relationship table size canbe reduced; both from the memory consumption and from the signalingconsumption perspective, if the candidate beams are wide and the numberof beams is lower. In some network deployments, e.g., deploying NR inLTE frequency bands or in a high load and frequent handover area, it maybe preferable to configure the MRS to be always-on, so that potentiallymany UEs that are covered by the same mobility beams can continuouslytrack the quality of neighbour beams.

To report MRS measurements to nodes other than the serving node, and toresume uplink data transmission towards a new serving node, the UE needsto apply correct timing advance, which typically differs from the TA forthe current serving node. In a non-synched Network, the TA estimationalways needs to be performed. USS transmission is then configuredper-measurement in the MRS measurement command or statically by RRC. Thesame applies in synched macro NWs, where the ISD, Inter Site Distance,exceeds or is comparable to the CP length.

In a tightly synched Network with short ISDs (Inter Site Distances), onthe other hand, the TA towards the old serving node may also work wellfor a new serving node. The UE can deduce whether that is the case fromwhether the old downlink timing sync works for the new node. It would beefficient not to do new TA estimation unless really necessary. Thenetwork-controlled approach is that the network configures the UE totransmit the USS (or not) on a per-measurement basis in the MRSmeasurement command. TA is not estimated if the network estimates thatthe old and new nodes can share the same TA value, otherwise the UE isrequested to send USS. Alternatively, in a UE-controlled approach, theUE can omit sending USS in the uplink if it determines that no re-syncwas necessary to measure the new node's MRS. Here, the node still needsto reserve resources for USS reception.

If the TA is to be changed, this is conveyed using dPDCH or PCCH eitherover the old serving beam or from the new node (where the downlink isalready “operational” since the UE has synched to the MRS).

In MRS reporting solution c1 above, the USS may be sent in the uplinkand TA update in the downlink may be sent as part of the beam switchcommand and handshake.

In MRS reporting solutions c2 and c3 above, the UE sends the USS as partof the measurement report procedure towards an MRS-transmitting node,and receives a TA update as a separate message.

In some deployments, where the UE position may be determined with highaccuracy, the required TA correction when switching from old servingbeam to a new one may be retrieved from a previously collected database.The database is created based on previous TA measurements managedaccording to SON principles.

The mobility measurement sequences are essentially the same as in LTE.The mobility monitoring and triggering sequences are similar to those inLTE, but some details differ, e.g., the criteria of launching and theUE-specific signals available for mobility measurements. The MRSactivation sequence where reference signals (MRS) are activateddynamically in a UE-specific candidate beam set is a new procedure inNR. Activating and deactivating MRS on request, and in a UE specificmanner is critical for lean design. The main new challenge in NR is forthe network to decide which candidate MRSs are activated, and when. Thelatter aspect may be especially critical at high frequencies due toshadow fading. Some preparations and signaling may be needed in thenetwork when candidate beams are activated in several different nodes.Nevertheless, this procedure is transparent to the UE. The UE is onlyinformed about the measurement configuration and the UE reportsaccordingly, without having associated the beams with specific nodes.The TA update sequences can also be measured and adjusted in target nodeafter the switch command is first informed. Also, the additionalreconfiguration is probably required.

The beam switch triggering procedure differs depending on how MRS isdesigned and transmitted. More specifically there are three typicalcases:

-   -   The beam MRS is only activated when serving beam quality        degradation is detected. MRS for all relevant candidate beams in        the lookup table are activated, no matter if the beam is from        the same node or from a neighbouring node. The table building        can be part of the SON functions. The UE measures on all the        MRSs and sends the measurement report.    -   Either all the sector MRSs in the lookup table or the sector MRS        containing the serving beam for the active UE is configured and        transmitted periodically. UE can also keep track of the quality        of the transmitted sector MRS and report the quality        periodically or in an event-based manner.    -   The serving mobility beam is adapted to continuously track the        UE to maintain the maximum beam gain, which is similar to the        CSI-RS procedures. The UE reports an error signal between the        current serving beam direction and the estimated best beam        direction, using additional beams in the neighbourhood of the        serving beam.

Case 1 is more suitable for services without strict QoS requirements,while case 2 is more suitable for time critical service with additionaloverhead. (There are also hybrid options, e.g., activating all the MRSsin the lookup table for a given UE, with additional overhead.) In case3, with UE specific reference symbols, any modification of beam shapewithin one node can be transparent to the UE—no signaling is required,unless RX analog beamforming is applied in the UE side.

It is also possible to use uplink measurements to select downlink beam.On a high level, it can be assumed that such measurements are performedon demand, when a beam switch is deemed necessary. Hence, the concept ofa mobility event still applies, and some sort of trigger to start theevent is relied upon.

Since the downlink beam is being updated, it is natural to still monitorthe downlink performance, using any of the measurements described in theprevious section. For instance, CQI measured on CSI-RS or MRS may bemonitored.

Using uplink measurements to choose the access node used for downlinktransmission usually works well, providing that different access nodesuse the same transmit power and have the same antenna capabilities.Otherwise, this has to be compensated for.

To use uplink measurements to select downlink beam within one node,reciprocity between uplink and downlink is desirable. Passive antennacomponents and the propagation medium are physically reciprocal for TXand RX, but active components and radio-frequency (RF) filters in the RXand TX paths typically exhibit asymmetries and phase variations that donot yield automatic reciprocity in all cases. However, by introducingadditional hardware design constraints and calibration procedures, anydesirable degree of reciprocity may be provided.

To obtain the uplink measurement, the network requests the UE to senduplink reference signals to the network. One possible reference signalfor mobility measurements is the USS. The USS can be detected not onlyby the serving node, but also by the neighbour nodes. The neighbournodes should hold transmissions of UEs that they are serving, to clearthe transmission resources where the USS will occur.

If the coverage situation is challenging, the UEs may need to use TXbeamforming to transmit the USS. In this case, the UE is required totransmit the USS in all candidate directions, and different USSidentities may be allocated to different uplink TX beams in the UE sideso that the network can feed back the best UE TX beam identities. If theUE cannot transmit in more than one direction simultaneously, the beamstransmissions may be time-multiplexed. The USS can be transmitted fromthe UE periodically or be event triggered (when the quality of the linkbeams degrades). Such beam sweep configuration is more complicated inthe uplink than in the downlink, due to the irregular UE antenna arraylayout. Suitable sweep patterns may be determined in several ways usingprior calibration or on-the-fly learning by the UE.

In the network, the candidate access node attempts to detect the USS indifferent beams, and selects the best beam. If analog beam forming isused by the network, the nodes cannot perform the measurement of a largenumber of beams in one USS period. The access node can scan the USSusing different RX beams sequentially. Coordination of UE TX and accessnode RX beam sweep patterns is complicated. Relying on this combinationshould only be considered if really mandated by the coveragerequirements.

There are some requirements on signaling between UE and network, whichinclude, e.g., the number of USS used in UE and the repetition periodfor network scanning. It may be assumed that the same procedure isadopted as for MRS configuration: configure USS transmission parametersusing RRC, and activate transmission using MAC.

There are several alternatives to perform downlink beam switching basedon the uplink measurement:

-   -   The narrow (link) beam can be selected directly based on the        uplink measurement.    -   The beam selection based on the uplink measurement decides the        mobility beam, and the narrow (link) beam can be selected based        on the complemented downlink measurement later.    -   The mobility beam is first decided by the uplink measurement        with a wider RX beam. After that, the narrow (link) beam can be        further decided by uplink measurements with narrow RX beam. When        deciding the narrow beam, the other RS might be measured in the        narrow beams that are located within, or in the vicinity of, the        selected RX beams in first part.

In the three beam-switching alternatives listed immediately above, thebeam-selection procedures (beam selection in the first alternative; widebeam selection in the second and third alternatives) are similar/ Anexample beam-selection procedure is illustrated in FIG. 12. Theprocedure of the beam selection based on the uplink measurement canbriefly be expressed as follows:

-   -   Trigger beam switch    -   Activate USS reception between neighbour nodes in relevant beams    -   Activate USS transmission in UE    -   Perform USS measurement in network    -   Determine the best beam based on the measurement report    -   Prepare beam switch if needed    -   Issue beam switch command if needed

As said previously, the USS can be transmitted from the UE periodically,or in an event-triggered manner. If the USS is transmitted periodicallyaccording to the early configuration, steps 1-3 can be ignored. If atiming advance update is needed, the TA value can be obtained from theUSS measurement and the new TA value can be informed to UE during beamswitch command.

For the narrow (link) beam selection that follows the mobility beamselection in the third downlink beam-switching alternative listed above,there is only one small difference, where the beams from neighbour nodeare not involved. It is a kind of intra-node beam selection, which isillustrated in FIG. 13. Here the “USS” could also be other type ofreference, such as RRS. The complemented downlink measurement in thesecond alternative above is similar to the intra-Node beam switch incase 2 of downlink measurement based method.

Described in this section are several additional techniques thatcomplement the techniques descried above. In various embodiments, anyone or more of these additional techniques may be implemented along withany combination of the techniques described above.

In NR, the amount of CSI generally increases with the number ofantennas/beams, meaning that the number of evaluations ofbeams/hypothesis performed by the UE can increase accordingly. This willin turn lead to an increase in UE power consumption.

One approach to address this, and to thus lower UE power consumption, isto have at least two reporting modes for CSI. One mode is a mode wherethe UE or other wireless device seeks the “best” transmissionconfiguration. This may be regarded as a “default” or “legacy” mode.Another mode may be referred to as a “low-power mode,” and is based onthe use of a threshold for the quality of the reported CSI (e.g., PMI).In this mode, the UE reports (to the wireless network) the first CSI/PMIthat meets a quality threshold requirement. Thus, rather than findingthe absolute best possible transmission configuration, the UE insteadfinds one that is sufficient to meet the quality threshold requirement,and reports it, reducing UE power consumption by not necessarily seekingthe absolute best possible transmission configuration. In certainembodiments, the UE may select the threshold for the quality of thereported CSI by itself, based on pre-programmed quality thresholds orother selection criteria. In alternative embodiments, the UE may receivea direction from the network as to the threshold for the quality of thereported CSI, and select the directed threshold.

In some embodiments, this low power mode may involve the UE onlyscanning a subset of the PMI, for example. This low power mode may alsoinvolve the UE turning off one or more receiver/transmitter chains or,more generally, switching one or more receiver and/or transmittercircuits to a low-power state while operating in the low power mode,such that the circuits consume less power in this low-power staterelative to their power consumption in the default mode. This low-powermode allows the evaluations of beams to be discontinued once asufficiently good beam is found, saving power consumption. An advantageof this approach is that for most signaling of small packets, the UEscan use a CSI reporting mode that saves a significant amount of energy.

In NR, a UE operating in dormant mode (e.g., RRC_CONNECTED DORMANTstate) searches for synchronization signals and other systeminformation, as was described in detail in sections above. In a systemwhere beamforming is in use, the UE searches for these synchronizationsignals and other system information across an interval of possibleresources, where that interval covers various combinations of time,frequency, and spatial beam. Note that this freedom with respect toresources does not exist in LTE.

A potential problem with this is that a dormant UE may need to stayawake for much longer periods to perform this searching, as compared towhen operating in LTE. This can have a negative impact on powerconsumption by the UE.

This problem may be addressed, in some embodiments, by having the UE go(back) to sleep as soon as it has received sufficiently good systeminformation and/or synchronization, where “sufficiently good” isdetermined by meeting a predetermined threshold or thresholds, withoutnecessarily searching over an entire predetermined search interval. Thisapproach allows the UE to realize power savings, especially inenvironments with good signals.

FIG. 14 is a process flow diagram illustrating an example methodaccording to this approach. As shown at block 1410, the method beginswith performing a measurement and/or demodulating/decoding, forsynchronization and/or system information, on one of a predetermined setof resources, where the resources are defined by one or more of beam,timing, and frequency. As shown at block 1420, the method furtherincludes determining whether sufficient synchronization and/or systeminformation has been obtained, as a result of the measurement and/ordemodulating/decoding on the current resource. If so, the method furtherincludes, as shown at block 1430, performing one or more actions basedon the measurement, if and to the extent that such an action isrequired, and going back to “sleep,” where “sleep” refers to alower-power mode of operation for the UE's circuitry, as compared to theoperating mode in which the measurements are actively performed. If, onthe other hand, it is determined that sufficient synchronization and/orinformation is not obtained, a next resource from the predetermined setof resources is assigned, as shown at block 1440, and the measuringand/or demodulating/decoding step shown in block 1410 is repeated.

An advantage of this technique is that UE power consumption in dormantmode may be reduced, in some cases to lower levels than achieved inconventional LTE operation. Note that “dormant mode” as used hereinrefers generally to a mode where a wireless device intermittentlyactivates receiver circuitry to monitor and/or measure signals,deactivating at least parts of the receiver circuitry in between thesemonitoring/measuring intervals. These periods where some of thecircuitry is deactivated may be referred to as “sleep” periods. In thediscussion above, NR is described as having a dormant mode referred toas RRC_CONNECTED DORMANT state. However, it will be appreciated thatthere may be one or several dormant modes supported by any givennetwork, with names that vary.

FIG. 15 illustrates another example process, involving a UE dormant modemeasurement procedure where beamformed cell information signals arereceived and processed according. Below, the steps in the figure areexplained in detail.

As shown at block 1510, a UE in dormant mode triggers a measurementoccasion based on any of various triggers. For a typical cellularsystem, this may be periodic with a period on the order of 1 second.

As shown at block 1520, the UE forms a list of cell information signalsand corresponding radio resources, where this list represents thosesignals and resources it is already aware of, or which it knows may bepresent. The radio resources can be beams, time intervals, and otherradio resource groups (such as OFDM resource elements, for example)where the cell information signals may be present.

As shown at block 1530, the UE sorts the resource and signal list in anorder based on for example (but not limited to):

-   -   Radio resource timing (first signals first etc.)    -   Known signal quality or measurement property from previous        measurement occasions    -   Information of likelihood of usefulness from other sources, cell        neighbour lists, other measurements, etc.

The sort order is so that the highest prioritized cell informationsignal (or resource) is first in the list.

As shown at block 1540, the UE uses its radio receiver to receive radioresources for the first item(s) in the list. While receiving this, themeasurement signal processing of previously collected resource may stillbe ongoing.

As shown at block 1550, the UE measures the desured signal propertiesfrom the collected radio resources. These may include (but are notlimited to) any one or more of:

-   -   Received signal power    -   Received signal SINR or SNR    -   Decodability of cell information    -   Decoded information such as paging information from the cellular        network.

As shown at block 1560, the UE decides, based on one or more of themeasured signal properties from 1550, whether the measurements collectedso far are “good enough” to stop measuring and cell search activities.If not, the measurements continue, as shown at block 1540. “Good enough”generally refers to the satisfaction of one or more predeterminedcriterion, which may include one or more of:

-   -   The received power, SINR or SNR being above a certain threshold    -   That cell information can be properly decoded    -   That something in the cell information indicates that a change        in mode is needed (for example a paging indication).

“Good enough” can furthermore be that a given number, e.g. 3, of themeasured cells are detected to be “Good cells”.

As shown at block 1570, determining that the measured signals are “goodenough” leads to an end of the measurement occasion. The UE then revertsto its normal procedures, which may include reporting measurements,deactivating one or more receiver circuits, etc.

A key aspect of the solution illustrated in FIG. 15 is that a UE in acellular system with beamformed cell information, and in dormant mode,collects measurements for each measurement occasion only up until apoint where the collected information is “good enough”. This allows theUE to save power by going back to sleep before doing an exhaustivesearch for all possible cell information signals.

FIG. 16 shows another example method, implemented by a UE or otherwireless device, for operating in a wireless communications network.This method is similar, at least in some respects, to the previouslyillustrated methods—it will be appreciated that features of this methodmay be mixed and matched, as appropriate with features of the methodsdescribed above.

The method 1600 shown in FIG. 16 is carried out while the UE isoperating in a dormant mode, wherein operating in the dormant modecomprises intermittently activating receiver circuitry to monitor and/ormeasure signals. This dormant mode may be, for example, theRRC_CONNECTED DORMANT state discussed earlier. The UE carries out thesteps shown in FIG. 16 while in this dormant mode, and while thereceiver circuitry is activated.

As shown at block 1610, the UE performs a measurement on each of aplurality of resources from a predetermined set of resources, ordemodulates and decodes information from each of a plurality ofresources from a predetermined set of resources, where the resources inthe predetermined set of resources are each defined by one or more of abeam, a timing, and a frequency. In some embodiments, the resources inthis predetermined set of resources are each defined as a beam. Each ofthese may represent a receiver beam (where the UE is “listening” indifferent directions using a particular combination of antennas andcombining weights) or a particular transmitter beam as formed by anaccess node, or a combination of both.

As shown at block 1620, the method further includes evaluating themeasurement or the demodulated and decoded information for each of theplurality of resources against a predetermined criterion. As shown atblock 1630, the UE then discontinues the performing and evaluating ofmeasurements, or discontinues the demodulating and decoding andevaluation of information, in response to determining that thepredetermined criterion is met, such that one or more resources in thepredetermined set of resources are neither measured nor demodulated anddecoded. Finally, as shown at block 1640, the method further comprisesdeactivating the activated receiver circuitry, further in response todetermining that the predetermined criterion is met. The steps in thefigure may be repeated at the next occurrence of a triggering event thatre-activates the receiver circuitry, in some embodiments, for exampleupon the periodic expiration of a dormant mode timer.

In some embodiments, the predetermined criterion comprises one or moreof the following: that a received power level, or a measuredsignal-to-interference-plus-noise ratio (SINR), or a signal-to-noiseratio (SNR) is above a predetermined threshold, for one or for apredetermined number of resources; that cell information can becorrectly decoded from one or for a predetermined number of resources;and that decoded information from one or for a predetermined number ofresources instructs a change in operation for the wireless device.

In some embodiments, the discontinuing is performed in response todetermining that the predetermined criterion is met for one of theresources. In some embodiments, the method further comprises, prior tosaid performing or demodulating and decoding, and prior to saidevaluating, discontinuing, and deactivating, determining a priorityorder for the predetermined set of resources, from highest to lowest,wherein said performing or demodulating and decoding is according to thepriority order, from highest to lowest. This determining the priorityorder for the predetermined set of resources may be based on one or moreof any of the following, for example: radio resource timing for one ormore of the resources; and measured signal qualities or measurementproperties from previous measurements of one or more of the resources.In some embodiments, determining the priority order for thepredetermined set of resources is based on information regardinglikelihood of usefulness for one or more of the resources, theinformation being received from other sources or cell neighbour lists.

In this section, some of the many detailed techniques and proceduresdescribed above are generalized and applied to specific methods, networknodes, and wireless devices. Each of these methods, radio networkequipment, and wireless devices, as well as the numerous variants ofthem that are described in the more detailed description above, may beregarded as an embodiment of the present invention. It should beunderstood that the particular groupings of these features describedbelow are examples—other groupings and combinations are possible, asevidenced by the preceding detailed discussion.

Note that in the discussion that follows and in the claims appendedhereto, the use of labels “first,” “second,” “third,” etc., is meantsimply to distinguish one item from another, and should not beunderstood to indicate a particular order or priority, unless thecontext clearly indicates otherwise.

As used herein, “wireless device” refers to a device capable,configured, arranged and/or operable to communicate wirelessly withnetwork equipment and/or another wireless device. In the presentcontext, communicating wirelessly involves transmitting and/or receivingwireless signals using electromagnetic signals. In particularembodiments, wireless devices may be configured to transmit and/orreceive information without direct human interaction. For instance, awireless device may be designed to transmit information to a network ona predetermined schedule, when triggered by an internal or externalevent, or in response to requests from the network. Generally, awireless device may represent any device capable of, configured for,arranged for, and/or operable for wireless communication, for exampleradio communication devices. Examples of wireless devices include, butare not limited to, user equipment (UE) such as smart phones. Furtherexamples include wireless cameras, wireless-enabled tablet computers,laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USBdongles, and/or wireless customer-premises equipment (CPE).

As one specific example, a wireless device may represent a UE configuredfor communication in accordance with one or more communication standardspromulgated by the 3rd Generation Partnership Project (3GPP), such as3GPP's GSM, UMTS, LTE, and/or 5G standards. As used herein, a “userequipment” or “UE” may not necessarily have a “user” in the sense of ahuman user who owns and/or operates the relevant device. Instead, a UEmay represent a device that is intended for sale to, or operation by, ahuman user but that may not initially be associated with a specifichuman user. It should also be appreciated that in the previous detaileddiscussion, the term “UE” is used, for convenience, even more generally,so as to include, in the context of the NR network, any type of wirelessdevice that accesses and/or is served by the NR network, whether or notthe UE is associated with a “user” per se. Thus, the term “UE” as usedin the above detailed discussion includes machine-type-communication(MTC) devices (sometimes referred to as machine-to-machine, or M2Mdevices), for example, as well as handsets or wireless devices that maybe associated with a “user.”

Some wireless devices may support device-to-device (D2D) communication,for example by implementing a 3GPP standard for sidelink communication,and may in this case be referred to as D2D communication devices.

As yet another specific example, in an Internet of Things (IOT)scenario, a wireless device may represent a machine or other device thatperforms monitoring and/or measurements, and transmits the results ofsuch monitoring and/or measurements to another wireless device and/or anetwork equipment. A wireless device may in this case be amachine-to-machine (M2M) device, which may in a 3GPP context be referredto as a machine-type communication (MTC) device. As one particularexample, a wireless device may be a UE implementing the 3GPP narrow bandinternet of things (NB-IoT) standard. Particular examples of suchmachines or devices are sensors, metering devices such as power meters,industrial machinery, or home or personal appliances, e.g.refrigerators, televisions, personal wearables such as watches etc. Inother scenarios, a wireless device may represent a vehicle or otherequipment that is capable of monitoring and/or reporting on itsoperational status or other functions associated with its operation.

A wireless device as described above may represent the endpoint of awireless connection, in which case the device may be referred to as awireless terminal. Furthermore, a wireless device as described above maybe mobile, in which case it may also be referred to as a mobile deviceor a mobile terminal.

Although it will be appreciated that specific embodiments of thewireless devices discussed herein may include any of various suitablecombinations of hardware and/or software, a wireless device configuredto operate in the wireless communications networks described hereinand/or according to the various techniques described herein may, inparticular embodiments, be represented by the example wireless device1000 shown in FIG. 17.

As shown in FIG. 17, example wireless device 1000 includes an antenna1005, radio front-end circuitry 1010, and processing circuitry 1020,which in the illustrated example includes a computer-readable storagemedium 1025, e.g., one or more memory devices. Antenna 1005 may includeone or more antennas or antenna arrays, and is configured to send and/orreceive wireless signals, and is connected to radio front-end circuitry1010. In certain alternative embodiments, wireless device 1000 may notinclude antenna 1005, and antenna 1005 may instead be separate fromwireless device 1000 and be connectable to wireless device 1000 throughan interface or port.

Radio front-end circuitry 1010, which may comprise various filters andamplifiers, for example, is connected to antenna 1005 and processingcircuitry 1020 and is configured to condition signals communicatedbetween antenna 1005 and processing circuitry 1020. In certainalternative embodiments, wireless device 1000 may not include radiofront-end circuitry 1010, and processing circuitry 1020 may instead beconnected to antenna 1005 without radio front-end circuitry 1010. Insome embodiments, radio-frequency circuitry 1010 is configured to handlesignals in multiple frequency bands, in some cases simultaneously.

Processing circuitry 1020 may include one or more of radio-frequency(RF) transceiver circuitry 1021, baseband processing circuitry 1022, andapplication processing circuitry 1023. In some embodiments, the RFtransceiver circuitry 1021, baseband processing circuitry 1022, andapplication processing circuitry 1023 may be on separate chipsets. Inalternative embodiments, part or all of the baseband processingcircuitry 1022 and application processing circuitry 1023 may be combinedinto one chipset, and the RF transceiver circuitry 1021 may be on aseparate chipset. In still alternative embodiments, part or all of theRF transceiver circuitry 1021 and baseband processing circuitry 1022 maybe on the same chipset, and the application processing circuitry 1023may be on a separate chipset. In yet other alternative embodiments, partor all of the RF transceiver circuitry 1021, baseband processingcircuitry 1022, and application processing circuitry 1023 may becombined in the same chipset. Processing circuitry 1020 may include, forexample, one or more central processing units (CPUs), one or moremicroprocessors, one or more application-specific integrated circuits(ASICs), and/or one or more field programmable gate arrays (FPGAs).

In particular embodiments, some or all of the functionality describedherein as relevant to a user equipment, MTC device, or other wirelessdevice may be embodied in a wireless device or, as an alternative, maybe embodied by the processing circuitry 1020 executing instructionsstored on a computer-readable storage medium 1025, as shown in FIG. 17.In alternative embodiments, some or all of the functionality may beprovided by the processing circuitry 1020 without executing instructionsstored on a computer-readable medium, such as in a hard-wired manner. Inany of those particular embodiments, whether executing instructionsstored on a computer-readable storage medium or not, the processingcircuitry 1020 can be said to be configured to perform the describedfunctionality. The benefits provided by such functionality are notlimited to the processing circuitry 1020 alone or to other components ofthe wireless device, but are enjoyed by the wireless device as a whole,and/or by end users and the wireless network generally.

The processing circuitry 1020 may be configured to perform anydetermining operations described herein. Determining as performed byprocessing circuitry 1020 may include processing information obtained bythe processing circuitry 1020 by, for example, converting the obtainedinformation into other information, comparing the obtained informationor converted information to information stored in the wireless device,and/or performing one or more operations based on the obtainedinformation or converted information, and as a result of said processingmaking a determination.

Antenna 1005, radio front-end circuitry 1010, and/or processingcircuitry 1020 may be configured to perform any transmitting operationsdescribed herein. Any information, data and/or signals may betransmitted to a network equipment and/or another wireless device.Likewise, antenna 1005, radio front-end circuitry 1010, and/orprocessing circuitry 1020 may be configured to perform any receivingoperations described herein as being performed by a wireless device. Anyinformation, data and/or signals may be received from a networkequipment and/or another wireless device

Computer-readable storage medium 1025 is generally operable to storeinstructions, such as a computer program, software, an applicationincluding one or more of logic, rules, code, tables, etc. and/or otherinstructions capable of being executed by a processor. Examples ofcomputer-readable storage medium 1025 include computer memory (forexample, Random Access Memory (RAM) or Read Only Memory (ROM)), massstorage media (for example, a hard disk), removable storage media (forexample, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or anyother volatile or non-volatile, non-transitory computer-readable and/orcomputer-executable memory devices that store information, data, and/orinstructions that may be used by processing circuitry 1020. In someembodiments, processing circuitry 1020 and computer-readable storagemedium 1025 may be considered to be integrated.

Alternative embodiments of the wireless device 1000 may includeadditional components beyond those shown in FIG. 17 that may beresponsible for providing certain aspects of the wireless device'sfunctionality, including any of the functionality described hereinand/or any functionality necessary to support the solution describedabove. As just one example, wireless device 1000 may include inputinterfaces, devices and circuits, and output interfaces, devices andcircuits. Input interfaces, devices, and circuits are configured toallow input of information into wireless device 1000, and are connectedto processing circuitry 1020 to allow processing circuitry 1020 toprocess the input information. For example, input interfaces, devices,and circuits may include a microphone, a proximity or other sensor,keys/buttons, a touch display, one or more cameras, a USB port, or otherinput elements. Output interfaces, devices, and circuits are configuredto allow output of information from wireless device 1000, and areconnected to processing circuitry 1020 to allow processing circuitry1020 to output information from wireless device 1000. For example,output interfaces, devices, or circuits may include a speaker, adisplay, vibrating circuitry, a USB port, a headphone interface, orother output elements. Using one or more input and output interfaces,devices, and circuits, wireless device 1000 may communicate with endusers and/or the wireless network, and allow them to benefit from thefunctionality described herein.

As another example, wireless device 1000 may include power supplycircuitry 1030. The power supply circuitry 1030 may comprise powermanagement circuitry. The power supply circuitry may receive power froma power source, which may either be comprised in, or be external to,power supply circuitry 1030. For example, wireless device 1000 maycomprise a power source in the form of a battery or battery pack whichis connected to, or integrated in, power supply circuitry 1030. Othertypes of power sources, such as photovoltaic devices, may also be used.

As a further example, wireless device 1000 may be connectable to anexternal power source (such as an electricity outlet) via an inputcircuitry or interface such as an electrical cable, whereby the externalpower source supplies power to power supply circuitry 1030.

Power supply circuitry 1030 may be connected to radio front-endcircuitry 1010, processing circuitry 1020, and/or computer-readablestorage medium 1025 and be configured to supply wireless device 1000,including processing circuitry 1020, with power for performing thefunctionality described herein.

Wireless device 1000 may also include multiple sets of processingcircuitry 1020, computer-readable storage medium 1025, radio circuitry1010, and/or antenna 1005 for different wireless technologies integratedinto wireless device 1000, such as, for example, GSM, WCDMA, LTE, NR,WiFi, or Bluetooth wireless technologies. These wireless technologiesmay be integrated into the same or different chipsets and othercomponents within wireless device 1000.

Wireless device 1000, in various embodiments, is adapted to carry outany of a variety of combinations of the features and techniquesdescribed herein. In some embodiments, for example, processing circuitry1020, e.g., using antenna 1005 and radio front-end circuitry 1010, isadapted to, while operating in dormant mode, and while receivercircuitry is activated, perform a measurement on each of a plurality ofresources from a predetermined set of resources or demodulating anddecoding information from each of a plurality of resources from apredetermined set of resources, where the resources in the predeterminedset of resources are each defined by one or more of a beam, a timing,and a frequency. The processing circuitry 1020 may be further adapted toevaluate the measurement or the demodulated and decoded information foreach of the plurality of resources against a predetermined criterion,and to then discontinue the performing and evaluating of measurements,or discontinue the demodulating and decoding and evaluation ofinformation, in response to determining that the predetermined criterionis met, such that one or more resources in the predetermined set ofresources are neither measured nor demodulated and decoded. Theprocessing circuitry 1020 may be further adapted to deactivate theactivated receiver circuitry, further in response to determining thatthe predetermined criterion is met.

Once again, the wireless devices adapted to operate in a dormant modeaccording to any of the several techniques described above may befurther adapted to carry out one or more of the several other techniquesdescribed herein. Thus, for example, the resources in the predeterminedset of resources may each be defined as a beam, in some embodiments, andin various embodiments the predetermined criterion may comprise one ormore of the following: that a received power level, or a measuredsignal-to-interference-plus-noise ratio (SINR), or a signal-to-noiseratio (SNR) is above a predetermined threshold, for one or for apredetermined number of resources; that cell information can becorrectly decoded from one or for a predetermined number of resources;that decoded information from one or for a predetermined number ofresources instructs a change in operation for the wireless device.

In some embodiments, the wireless device is adapted to carry out saiddiscontinuing in response to determining that the predeterminedcriterion is met for one of the resources. In some of these and in someother embodiments, the wireless device is further adapted to, prior tosaid performing or demodulating and decoding, and prior to saidevaluating, discontinuing, and deactivating, determine a priority orderfor the predetermined set of resources, from highest to lowest, whereinthe wireless device is adapted to carry out said performing ordemodulating and decoding is according to the priority order, fromhighest to lowest. In some of these latter embodiments, the wirelessdevice is adapted to determine the priority order for the predeterminedset of resources based on one or more of: radio resource timing for oneor more of the resources; and measured signal qualities or measurementproperties from previous measurements of one or more of the resources.In some of these and in some other embodiments, the wireless device isadapted to determine the priority order for the predetermined set ofresources based on information regarding likelihood of usefulness forone or more of the resources, said information being received from othersources or cell neighbour lists.

As used herein, the term “network equipment” refers to equipmentcapable, configured, arranged and/or operable to communicate directly orindirectly with a wireless device and/or with other equipment in thewireless communication network that enable and/or provide wirelessaccess to the wireless device. Examples of network equipment include,but are not limited to, access points (APs), in particular radio accesspoints. Network equipment may represent base stations (BSs), such asradio base stations. Particular examples of radio base stations includeNode Bs, and evolved Node Bs (eNBs). Base stations may be categorizedbased on the amount of coverage they provide (or, stated differently,their transmit power levels) and may then also be referred to as femtobase stations, pico base stations, micro base stations, or macro basestations. “Network equipment” also includes one or more (or all) partsof a distributed radio base station such as centralized digital unitsand/or remote radio units (RRUs), sometimes referred to as Remote RadioHeads (RRHs). Such remote radio units may or may not be integrated withan antenna as an antenna integrated radio. Parts of a distributed radiobase stations may also be referred to as nodes in a distributed antennasystem (DAS).

As a particular non-limiting example, a base station may be a relay nodeor a relay donor node controlling a relay.

Yet further examples of network equipment include multi-standard radio(MSR) radio equipment such as MSR BSs, network controllers such as radionetwork controllers (RNCs) or base station controllers (BSCs), basetransceiver stations (BTSs), transmission points, transmission nodes,Multi-cell/multicast Coordination Entities (MCEs), core network nodes(e.g., Mobility Switching Centers or MSCs, Mobility Management Entitiesor MMEs), Operation and Maintenance (O&M) nodes, Operation and SupportSystem (OSS) nodes, SON nodes, positioning nodes (e.g., E-SMLCs), and/orMDTs. More generally, however, network equipment may represent anysuitable device (or group of devices) capable, configured, arranged,and/or operable to enable and/or provide a wireless device access to thewireless communication network or to provide some service to a wirelessdevice that has accessed the wireless communication network.

As used herein, the term “radio network equipment” is used to refer tonetwork equipment that includes radio capabilities. Thus, examples ofradio network nodes are the radio base stations and radio access pointsdiscussed above. It will be appreciated that some radio networkequipment may comprise equipment that is distributed—such as thedistributed radio base stations (with RRHs and/or RRUs) discussed above.It will be appreciated that the various references herein to eNBs,eNodeBs, Node Bs, and the like are referring to examples of radionetwork equipment. It should also be understood that the term “radionetwork equipment” as used herein may refer to a single base station ora single radio node, in some cases, or to multiple base stations ornodes, e.g., at different locations. In some cases, this document mayrefer to an “instance” of radio network equipment, to more clearlydescribe certain scenarios where multiple distinct embodiments orinstallations of radio equipment are involved. However, the lack ofreference to an “instance” in connection with a discussion of radionetwork equipment should not be understood to mean that only a singleinstance is being referred to. A given instance of radio networkequipment may alternatively be referred to as a “radio network node,”where the use of the word “node” denotes that the equipment referred tooperate as a logical node in a network, but does not imply that allcomponents are necessarily co-located.

While radio network equipment may include any suitable combination ofhardware and/or software, an example of an instance of radio networkequipment 1100 is illustrated in greater detail by FIG. 18. As shown inFIG. 18, example radio network equipment 1100 includes an antenna 1105,radio front-end circuitry 1110, and processing circuitry 1120, which inthe illustrated example includes a computer-readable storage medium1025, e.g., one or more memory devices. Antenna 1105 may include one ormore antennas or antenna arrays, and is configured to send and/orreceive wireless signals, and is connected to radio front-end circuitry1110. In certain alternative embodiments, radio network equipment 1100may not include antenna 1005, and antenna 1005 may instead be separatefrom radio network equipment 1100 and be connectable to radio networkequipment 1100 through an interface or port. In some embodiments, all orparts of radio front-end circuitry 1110 may be located at one or severallocations apart from the processing circuitry 1120, e.g., in a RRH orRRU. Likewise, portions of processing circuitry 1120 may be physicallyseparated from one another. Radio network equipment 1100 may alsoinclude communication interface circuitry 1140 for communicating withother network nodes, e.g., with other radio network equipment and withnodes in a core network.

Radio front-end circuitry 1110, which may comprise various filters andamplifiers, for example, is connected to antenna 1105 and processingcircuitry 1120 and is configured to condition signals communicatedbetween antenna 1105 and processing circuitry 1120. In certainalternative embodiments, radio network equipment 1100 may not includeradio front-end circuitry 1110, and processing circuitry 1120 mayinstead be connected to antenna 1105 without radio front-end circuitry1110. In some embodiments, radio-frequency circuitry 1110 is configuredto handle signals in multiple frequency bands, in some casessimultaneously.

Processing circuitry 1120 may include one or more of RF transceivercircuitry 1121, baseband processing circuitry 1122, and applicationprocessing circuitry 1123. In some embodiments, the RF transceivercircuitry 1121, baseband processing circuitry 1122, and applicationprocessing circuitry 1123 may be on separate chipsets. In alternativeembodiments, part or all of the baseband processing circuitry 1122 andapplication processing circuitry 1123 may be combined into one chipset,and the RF transceiver circuitry 1121 may be on a separate chipset. Instill alternative embodiments, part or all of the RF transceivercircuitry 1121 and baseband processing circuitry 1122 may be on the samechipset, and the application processing circuitry 1123 may be on aseparate chipset. In yet other alternative embodiments, part or all ofthe RF transceiver circuitry 1121, baseband processing circuitry 1122,and application processing circuitry 1123 may be combined in the samechipset. Processing circuitry 1120 may include, for example, one or morecentral CPUs, one or more microprocessors, one or more ASICs, and/or oneor more field FPGAs.

In particular embodiments, some or all of the functionality describedherein as being relevant to radio network equipment, radio basestations, eNBs, etc., may be embodied in radio network equipment or, asan alternative may be embodied by the processing circuitry 1120executing instructions stored on a computer-readable storage medium1125, as shown in FIG. 18. In alternative embodiments, some or all ofthe functionality may be provided by the processing circuitry 1120without executing instructions stored on a computer-readable medium,such as in a hard-wired manner. In any of those particular embodiments,whether executing instructions stored on a computer-readable storagemedium or not, the processing circuitry can be said to be configured toperform the described functionality. The benefits provided by suchfunctionality are not limited to the processing circuitry 1120 alone orto other components of the radio network equipment, but are enjoyed bythe radio network equipment 1100 as a whole, and/or by end users and thewireless network generally.

The processing circuitry 1120 may be configured to perform anydetermining operations described herein. Determining as performed byprocessing circuitry 1120 may include processing information obtained bythe processing circuitry 1120 by, for example, converting the obtainedinformation into other information, comparing the obtained informationor converted information to information stored in the radio networkequipment, and/or performing one or more operations based on theobtained information or converted information, and as a result of saidprocessing making a determination.

Antenna 1105, radio front-end circuitry 1110, and/or processingcircuitry 1120 may be configured to perform any transmitting operationsdescribed herein. Any information, data and/or signals may betransmitted to any network equipment and/or a wireless device. Likewise,antenna 1105, radio front-end circuitry 1110, and/or processingcircuitry 1120 may be configured to perform any receiving operationsdescribed herein as being performed by a radio network equipment. Anyinformation, data and/or signals may be received from any networkequipment and/or a wireless device.

Computer-readable storage medium 1125 is generally operable to storeinstructions, such as a computer program, software, an applicationincluding one or more of logic, rules, code, tables, etc. and/or otherinstructions capable of being executed by a processor. Examples ofcomputer-readable storage medium 1125 include computer memory (forexample, RAM or ROM), mass storage media (for example, a hard disk),removable storage media (for example, a CD or a DVD), and/or any othervolatile or non-volatile, non-transitory computer-readable and/orcomputer-executable memory devices that store information, data, and/orinstructions that may be used by processing circuitry 1120. In someembodiments, processing circuitry 1120 and computer-readable storagemedium 1125 may be considered to be integrated.

Alternative embodiments of the radio network equipment 1100 may includeadditional components beyond those shown in FIG. 18 that may beresponsible for providing certain aspects of the radio networkequipment's functionality, including any of the functionality describedherein and/or any functionality necessary to support the solutiondescribed above. As just one example, radio network equipment 1100 mayinclude input interfaces, devices and circuits, and output interfaces,devices and circuits. Input interfaces, devices, and circuits areconfigured to allow input of information into radio network equipment1100, and are connected to processing circuitry 1120 to allow processingcircuitry 1120 to process the input information. For example, inputinterfaces, devices, and circuits may include a microphone, a proximityor other sensor, keys/buttons, a touch display, one or more cameras, aUSB port, or other input elements. Output interfaces, devices, andcircuits are configured to allow output of information from radionetwork equipment 1100, and are connected to processing circuitry 1120to allow processing circuitry 1120 to output information from radionetwork equipment 1100. For example, output interfaces, devices, orcircuits may include a speaker, a display, a USB port, a headphoneinterface, or other output elements. Using one or more input and outputinterfaces, devices, and circuits, radio network equipment 1100 maycommunicate with end users and/or the wireless network, and allow themto benefit from the functionality described herein.

As another example, radio network equipment 1100 may include powersupply circuitry 1130. The power supply circuitry 1130 may comprisepower management circuitry. The power supply circuitry 1130 may receivepower from a power source, which may either be comprised in, or beexternal to, power supply circuitry 1130. For example, radio networkequipment 1100 may comprise a power source in the form of a battery orbattery pack which is connected to, or integrated in, power supplycircuitry 1130. Other types of power sources, such as photovoltaicdevices, may also be used. As a further example, radio network equipment1100 may be connectable to an external power source (such as anelectricity outlet) via an input circuitry or interface such as anelectrical cable, whereby the external power source supplies power topower supply circuitry 1130.

Power supply circuitry 1130 may be connected to radio front-endcircuitry 1110, processing circuitry 1120, and/or computer-readablestorage medium 1125 and be configured to supply radio network equipment1100, including processing circuitry 1120, with power for performing thefunctionality described herein.

Radio network equipment 1100 may also include multiple sets ofprocessing circuitry 1120, computer-readable storage medium 1125, radiocircuitry 1110, antenna 1105 and/or communication interface circuitry1140 for different wireless technologies integrated into radio networkequipment 1100, such as, for example, GSM, WCDMA, LTE, NR, WiFi, orBluetooth wireless technologies. These wireless technologies may beintegrated into the same or different chipsets and other componentswithin radio network equipment 1100.

One or more instances of the radio network equipment 1100 may be adaptedto carry out some or all of the techniques described herein, in any ofvarious combinations. It will be appreciated that in a given networkimplementation, multiple instances of radio network equipment 1100 willbe in use. In some cases, several instances of radio network equipment1100 at a time may be communicating with or transmitting signals to agiven wireless device or group of wireless devices. Thus, it should beunderstood that while many of the techniques described herein may becarried out by a single instance of radio network equipment 1100, thesetechniques may be understood as carried out by a system of one or moreinstances of radio network equipment 1100, in some cases in acoordinated fashion. The radio network equipment 1100 shown in FIG. 18is thus the simplest example of this system.

FIG. 19 illustrates an example functional module or circuit architectureas may be implemented in a wireless device 1000, e.g., based on theprocessing circuitry 1020. The illustrated embodiment at leastfunctionally includes a dormant mode module 1910 for controllingoperation of the wireless device 1000 in a dormant mode, whereinoperating in the dormant mode comprises intermittently activatingreceiver circuitry to monitor and/or measure signals. The embodimentfurther includes several other modules that operate while the wirelessdevice 1000 is in dormant mode and while the receiver circuitry isactivated, including a measurement module 1920 for performing ameasurement on each of a plurality of resources from a predetermined setof resources or demodulating and decoding information from each of aplurality of resources from a predetermined set of resources, where theresources in the predetermined set of resources are each defined by oneor more of a beam, a timing, and a frequency, and an evaluation module1930 for evaluating the measurement or the demodulated and decodedinformation for each of the plurality of resources against apredetermined criterion.

The illustrated embodiment further includes a discontinuing module 1940for discontinuing the performing and evaluating of measurements ordiscontinuing the demodulating and decoding and evaluation ofinformation, in response to determining that the predetermined criterionis met, such that one or more resources in the predetermined set ofresources are neither measured nor demodulated and decoded, and adeactivation module 1950 for deactivating the activated receivercircuitry, further in response to determining that the predeterminedcriterion is met.

In some embodiments of the wireless device 1000 as illustrated in FIG.19, the resources in the predetermined set of resources are each definedas a beam. In some embodiments, the predetermined criterion comprisesone or more of the following: that a received power level, or a measuredsignal-to-interference-plus-noise ratio (SINR), or a signal-to-noiseratio (SNR) is above a predetermined threshold, for one or for apredetermined number of resources; that cell information can becorrectly decoded from one or for a predetermined number of resources;that decoded information from one or for a predetermined number ofresources instructs a change in operation for the wireless device.

In some embodiments, discontinuing module 1940 is adapted to perform itsdiscontinuing in response to determining that the predeterminedcriterion is met for one of the resources.

In some embodiments, the wireless device 1000 further comprises adetermining module (not pictured) for determining, prior to theoperations carried out by the measurement module 1920, evaluating module1930, discontinuing module 1940, and deactivation module 1950, apriority order for the predetermined set of resources, from highest tolowest. In these embodiments, the operations carried out by themeasurement module are carried out according to the priority order, fromhighest to lowest. In some of these embodiments, the determining of thepriority order for the predetermined set of resources is based on one ormore of: radio resource timing for one or more of the resources; andmeasured signal qualities or measurement properties from previousmeasurements of one or more of the resources. In some of these and insome other embodiments, the determining of the priority order for thepredetermined set of resources is based on information regardinglikelihood of usefulness for one or more of the resources, thisinformation being received from other sources or cell neighbour lists.

What is claimed is:
 1. A method, in a wireless device, for operating ina wireless communications network, the method comprising: operating in adormant mode, wherein operating in the dormant mode comprisesintermittently activating receiver circuitry to monitor and/or measuresignals; and, while in dormant mode and while the receiver circuitry isactivated: performing a measurement on each of a plurality of resourcesfrom a predetermined set of resources or demodulating and decodinginformation from each of a plurality of resources from a predeterminedset of resources, where the resources in the predetermined set ofresources are each defined by one or more of a beam, a timing, and afrequency; evaluating the measurement or the demodulated and decodedinformation for each of the plurality of resources against apredetermined criterion; discontinuing the performing and evaluating ofmeasurements or discontinuing the demodulating and decoding andevaluation of information, in response to determining that thepredetermined criterion is met, such that one or more resources in thepredetermined set of resources are neither measured nor demodulated anddecoded; and deactivating the activated receiver circuitry, further inresponse to determining that the predetermined criterion is met.
 2. Themethod of claim 1, wherein the resources in the predetermined set ofresources are each defined as a beam.
 3. The method of claim 1, whereinthe predetermined criterion comprises one or more of the following: thata received power level or a measured signal-to-interference-plus-noiseratio (SINR) or a signal-to-noise ratio (SNR) is above a predeterminedthreshold, for one or for a predetermined number of resources; that cellinformation can be correctly decoded from one or for a predeterminednumber of resources; and that decoded information from one or for apredetermined number of resources instructs a change in operation forthe wireless device.
 4. The method of claim 1, wherein saiddiscontinuing is performed in response to determining that thepredetermined criterion is met for one of the resources.
 5. The methodof claim 1, further comprising, prior to said performing or demodulatingand decoding, and prior to said evaluating, discontinuing, anddeactivating, determining a priority order for the predetermined set ofresources, from highest to lowest, wherein said performing ordemodulating and decoding is according to the priority order, fromhighest to lowest.
 6. The method of claim 5, wherein determining thepriority order for the predetermined set of resources is based on one ormore of: radio resource timing for one or more of the resources; andmeasured signal qualities or measurement properties from previousmeasurements of one or more of the resources.
 7. The method of claim 5,wherein determining the priority order for the predetermined set ofresources is based on information regarding likelihood of usefulness forone or more of the resources, said information being received from othersources or cell neighbor lists.
 8. A wireless device for operation in awireless communications network, the wireless device comprising receivercircuitry and processing circuitry operatively coupled to the receivercircuitry and configured to: operate in a dormant mode, whereinoperating in the dormant mode comprises intermittently activating thereceiver circuitry to monitor and/or measure signals; and, while indormant mode and while the receiver circuitry is activated: perform ameasurement on each of a plurality of resources from a predetermined setof resources or demodulate and decode information from each of aplurality of resources from a predetermined set of resources, where theresources in the predetermined set of resources are each defined by oneor more of a beam, a timing, and a frequency; evaluate the measurementor the demodulated and decoded information for each of the plurality ofresources against a predetermined criterion; discontinue the performingand evaluating of measurements or discontinue the demodulating anddecoding and evaluation of information, in response to determining thatthe predetermined criterion is met, such that one or more resources inthe predetermined set of resources are neither measured nor demodulatedand decoded; and deactivate the activated receiver circuitry, further inresponse to determining that the predetermined criterion is met.
 9. Thewireless device of claim 8, wherein the resources in the predeterminedset of resources are each defined as a beam.
 10. The wireless device ofclaim 9, wherein the predetermined criterion comprises one or more ofthe following: that a received power level or a measuredsignal-to-interference-plus-noise ratio (SINR) or a signal-to-noiseratio (SNR) is above a predetermined threshold, for one or for apredetermined number of resources; that cell information can becorrectly decoded from one or for a predetermined number of resources;that decoded information from one or for a predetermined number ofresources instructs a change in operation for the wireless device. 11.The wireless device of claim 8, wherein the processing circuitry isconfigured to carry out said discontinuing in response to determiningthat the predetermined criterion is met for one of the resources. 12.The wireless device of claim 8, wherein the processing circuitry isfurther configured to, prior to said performing or demodulating anddecoding, and prior to said evaluating, discontinuing, and deactivating,determine a priority order for the predetermined set of resources, fromhighest to lowest, wherein the processing circuitry is configured tocarry out said performing or demodulating and decoding is according tothe priority order, from highest to lowest.
 13. The wireless device ofclaim 12, wherein the processing circuitry is configured to determinethe priority order for the predetermined set of resources based on oneor more of: radio resource timing for one or more of the resources; andmeasured signal qualities or measurement properties from previousmeasurements of one or more of the resources.
 14. The wireless device ofclaim 12, wherein the processing circuitry is configured to determinethe priority order for the predetermined set of resources based oninformation regarding likelihood of usefulness for one or more of theresources, said information being received from other sources or cellneighbor lists.